Mistaken for Cheating

Iago: Your wife's cheating on you.
Othello: She is? [kills wife] Damn, she wasn't really.

— Book A Minute, Othello

Similar to Mistaken for Gay, this is when a character is wrongly accused of cheating on his spouse or girlfriend because of a series of misinterpreted clues. Usually these clues look very suspicious (a bra left in his apartment, lipstick on his collar, a piece of Affair Hair, a romantic note) and the real story is hard to believe and/or involves secrets the accused character doesn't want to reveal. The wrongly accused may protest "Wait! I Can Explain!" or "It's Not What It Looks Like!" If the spouse or girlfriend is another major character, the conflict will be resolved; if the love interest is a Girl of the Week, she may storm off, thus ending the relationship.

Other possible dénouements include the love interest discovering a fact about the supposed partner thief that rules them out as a possible rival: for example, they're actually a relative, a member of an Incompatible Orientation, or in rare cases, even the wrong gender.

Sometimes the mistake can be made by an outside party, such as a concerned friend or relative or a Nosy Neighbor. One additional possible outcome in this case is that the suspected liaison is indeed happening, but everyone concerned is polyamorous or otherwise aware of and content with the situation.

One notable property of this trope is that it can be used on shows that, because of their genre or their scrutiny by Moral Guardians, could never use a plot that involved actual adultery. But you can get some of the same benefits from a story where a character wrongly believes that adultery is going on.

It can also be deliberately invoked if an outside party trying to invoke Relationship Sabotage.

See also Mistaken for Index and Intramarital Affair. Supertrope of Spy's Suspicious Spouse. Often part of an Idiot Plot; and can result in Poor Communication Kills, at least figuratively. May be resolved with The Grovel. Making this even worse is that if one is murdered by a Woman Scorned under this assumption. Can overlap with Imaginary Love Triangle, when that's the mistaken assumption that's made. May also overlap with Suspiciously Unclad Companion. Inverted into Totally Trusting Love Interest if the love interest doesn't even mistake it as cheating after seeing the thing that's Not What It Looks Like. For the other kind of cheating, see "Success Through Cheating" Accusation.

Example Subpages

Examples:

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Advertising

A cement mixer advertisement, based on an urban legend, has a married cement mixer driver come home to find a fancy convertible in his driveway and sees his wife excitedly hugging another man. He fills the car with cement in a fit of rage, only to find that the car was the prize in a lottery.
Jake from State Farm commercials:
- In "State of Unrest", featuring Jake from State Farm, a woman finds her husband on the phone with a (male) State Farm rep at 3am and assumes he's talking to another woman. She grabs the phone and starts talking to him.
  Husband: Yeah, I'm married. Does it matter?... You'd do that for me?... Really?... Yeah, I'd like that—
  Wife: Who are you talking to?
  Husband: It's Jake from State Farm. Sounds like a really good deal.
  Wife: Jake from State Farm at three in the morning? [grabs the phone] Who is this?!
  Husband: It's Jake from State Farm.
  Wife: What are you wearing, "Jake from State Farm"?
  [cut to State Farm office]
  Jake^*actual State Farm insurance agent: Uh...khakis?
  [cut to living room]
  Wife: She sounds hideous.
  Husband: Well, she's a guy, so...
- A variant of this ad instead features The Coneheads, with Beldar being suspected of infidelity by Prymaat due to the notion that no-one would contact "Planet State Farm" at "0300 hours." The joke is, of course, these are the Coneheads we are talking about, so it doesn't go quite the way the normal version does.
  Beldar: Correct I have a lifemate! Is that consequential? Hmm, ah...
  Prymaat: With whom are you communicating?
  Beldar: Jake from Planet State Farm!
  Prymaat: Jake from Planet State Farm? At 0300 hours? [takes the phone] State your identity.
  Beldar: It is Jake from Planet State Farm! Home of discount double-check.
  Prymaat: Describe your apparel, "Jake from Planet State Farm."
  Beldar: [hissing noises]
  [cut to State Farm office]
  Jake: Uh...khakis?
  [cut to living room]
  Prymaat: Khakis? Explain.
  Beldar: A dull Earthly garment covering male extremities.
  Prymaat: [quietly surprised] Sounds most appropriate.
  Beldar: Mm-hm.
- And another variant with the new Jake.
  Wife: What are you wearing, "Jake From State Farm"?
  [cut to State Farm office]
  Jake: Uh, khakis? (aside, to coworker^*the original Jake) Hey, do they ever ask you what you're wearing?
  Coworker: Uh, yeah.
  Jake: (to wife) Red sweater, button-up shirt...
A '90s commercial shows a couple kissing on a couch until a woman calls telling the guy she'll be coming over. The girlfriend slaps him in angry and walks out. The woman who called was revealed to be a chubby maid with a sultry voice.
Maid: [vacuuming] Hey sweetie, pick up your feet.
Man: [watching TV and drinking sully, over the noise] Thanks for coming!
A 1954 commerical for Bondex has a woman hearing over her husband that he's plotting to get rid of her and giving the new girl a mink coat. The detective in those commericals decided to investigate and found out what the husband was plotting. Turns out the husband was referring to their house needing a new coat of paint using the titular product.

Anime & Manga

Forms the basis of some of the plots in Ah! My Goddess, when Belldandy suspects Keiichi is cheating on her. In the end, it always turns out to be a Not What It Looks Like moment, or in Hild's cases, manipulating him and the goddesses in order to try to steal him away.
Played for intense drama in Akatsuki no Aria. Shiroyuki-sensei is a married man who has Hot for Student feelings for the titular Aria, but would never cheat on his ill wife Kimie with her. Bad thing, Kimie died all alone in a hospital when he was trying to help Aria with her bad hand, so Kimie's family does think he was fooling around with Aria while his wife was on her deathbed. Naturally, Shiroyuki feels TERRIBLE when he finds out.
Happens a lot in Baka and Test: Summon the Beasts to the two main guys, Akihisa Yoshii and Yuuji Sakamoto. In one hilarious incident, Shouko demands access to Yuuji's cellphone, and after she starts to strip him in order to find it, he gives it to her. She then finds a text written to him by Akihisa, asking if Yuuji would let him stay over at his place that night. She immediately assumes that they're in some kind of illicit relationship. Later the main characters go to his house for a study session (and to see why he didn't want to go home), and the two girls who like Akihisa immediately also start questioning him as to why there's women-related clothing and items in his apartment (which turns out to be his sister Akira's stuff, who's visiting him to make sure he's not goofing off).
Himeji: This bra isn't your size, Yoshi-kun...
In Bakuman。, Akito Takagi, seeking ideas on how to write female characters, meets fellow mangaka Yuriko "Ko Aoki" Aoki, but keeps the meetings secret from his girlfriend Kaya Miyoshi out of fear that she would get jealous over him turning elsewhere for advice. While there, he meets his former classmate and academic rival, Aiko Iwase, who gives him a copy of her book with a letter inside. Miyoshi then discovers the letter and becomes quite upset until the misunderstanding is cleared a few chapters later.
Black or White: Hanasaki, in an attempt to get the oblivious Shin more aware of putting himself in potentially compromising positions, comes on to him while visiting Shin and Shige's place. Then Crazy Jealous Guy Shige walks in to see Hanasaki seemingly about to kiss his boyfriend. Shin, innocently oblivious to the tension in the room, leaves to take a phone call, leaving Hanasaki to explain to a quietly furious Shige why what he saw was just him messing around and nothing to worry about.
Crossplay Love: Otaku x Punk: Shizuku got divorced after his wife found women's clothing and lipstick in Shizuku's room, and he couldn't bring himself to reveal he bought them for crossdressing.
A Cruel God Reigns:
- Happens between Jeremy and Vivi in the earlier chapters. Jeremy is forced into having sex with Greg so that he will marry his mother Sandra, and eventually Vivi notices the subtle differences in Jeremy's reactions to her affection, his kissing, reactions to being touched, suspicious reactions to being asked, etc. Although Jeremy does actually cheat on Vivi, it falls into this troupe because it is against his will and it affects him very negatively, eventually ending in Jeremy killing Greg by Make It Look Like an Accident and Vehicular Sabotage . Jeremy tries both I Can Explain and Not What It Looks Like to try to keep Vivi as his girlfriend.
- Also happens with Lilia. Greg suspected that she cheated on him while the two were in Boston and that Matt is an illegitimate child.
The first episode of Death Parade has an... extremely complicated example of this trope. The series takes place in what is essentially purgatory and the premise revolves around an Artificial Human who must decide whether people either get sent to an endless void or are allowed to be reincarnated. The first episode revolves around a newlywed husband and wife who died on their honeymoon. At first we're led to believe Machiko is a Gold Digger however a few moments later she explains to Takashi that he misunderstood everything. However it turns out she really did cheat on him, however only once and she regretted it. Then it's revealed that too was a lie. She never loved him and their unborn baby wasn't his. Machiko gets sent to the Void for their actions however the end of the episode implies she was actually lying about lying. She hated seeing her husband blame himself for killing their child so she pretended it wasn't his in order to have him rest in peace. Decim recognizes his mistake however it's too late to fix, and Machiko is cursed to all of eternity falling in an endless abyss.
IC In A Doll: "A Doll's House" focuses on an extremely Dysfunctional Family, the source of the dysfunction stemming from the mother being an abusive Education Mama who also emasculates her husband. She believes he's having an affair when she finds lipstick stains on his shirt that don't match any of the shades she owns. The stains belong to him. He's discovered dressing in feminine clothes makes him more comfortable and has secretly been going out at night, made-up to resemble one of the common robotic Dolls, to find some peace away from his unhappy home life. Unfortunately, the son believes the best way to make his family better is to get rid of this mysterious woman who is making his mom unhappy. The story ends with the son not realizing he's just murdered his own father.
Dragon Ball: In a filler episode, a master thief named Hasky attacks Yamcha with a sword to try to steal the Dragon Balls he was carrying. Yamcha fends her off, but then his girlfriend Bulma arrives on the scene. Bulma completely misinterprets the situation due to the angle she is seeing them and thinks Yamcha and Hasky are making out. She angrily throws a crate at Yamcha's head and storms off, allowing Hasky to knock Yamcha out and steal the Dragon Balls. Even after Goku stops Hasky, Bulma remains convinced Yamcha was unfaithful.
Dragon Ball Super: A jealous action star tries on Gohan and Videl, managing to get a picture of a pop idol kissing Gohan. Videl sees through it instantly, saying that she knows Gohan would never cheat on her, that there must be some circumstances behind the photo, and that the guy must be pathetic to think such a trick would break up her marriage.
I Want to Be a Wall: Played With. Gakurouta and Yuriko Hanazono are a gay man and an aroace woman in a lavender marriage, so there is no actual romantic attraction between them, but they do still have a very strong platonic bond. However, Gakurouta starts getting nervous when Yuriko starts frequently hanging out with another man and has a nightmare where she runs off and marries him as her new beard. But as it turns out he's actually Yuriko's friend from college, Momoya, who is engaged and had come to visit Yuriko both to plan his wedding and to collect some limited-edition file folders from a Prince of Table Tennis collaborative cafe event.
Chapter 97 of Kaguya-sama: Love Is War has Kashiwagi coming to the Student Council for help because she thinks her boyfriend is cheating on her with her best friend Maki. In something of a subversion, while her boyfriend wasn't cheating on her (he was asking for help about buying an anniversary present), Maki was trying break them up so she could have him for herself.
Kimagure Orange Road:
- Used in one of the OVA episodes, Message in Rouge (and the manga story it was based on). Madoka has an Heroic BSoD and runs away from home when she believes her beloved dad is cheating on her also beloved mom, staying in the Kasuga apartment when Kyousuke is home alone. It turns out Mr. Ayukawa was checking on the well-being of a co-worker who had a bad eye, and Mrs. Ayukawa knew it all the time.
- Played much more for laughs in the OVA that introduced Akane. She mistakenly believes Kyousuke is cheating on Hikaru with Madoka, goes on to give his "other woman" a piece of her mind... and is left starstruck by her.
Kyo Kara Maoh!: Wolfram is always accusing Yuuri of cheating and Yuuri never is.
Manami from Life (2002) mistakes her boyfriend for cheating when he's tutoring Ayumu. She gets her Japanese Delinquent lover to beat him up later.
Chapter 14 of Love Me For Who I Am starts with Suzu's boyfriend Haruto seeing him eating with Tetsu. Haruto gets the wrong idea and thinks that Tetsu is trying to steal his boyfriend.
Joséphine of the Rose (2011): Alexandre is led to think Joséphine cheated after he pays a visit to Martinique and many of her former friends claim she would take off her clothes for any man who asked. Joséphine is crestfallen, but his parents take her side and tell her they know that the rumors aren't true.
A Man and His Cat: Happened to Kobayashi before the story's events. He claims that his wife got the wrong idea, but not even his best friend Kanda fully believes him. Whatever happened between him and his wife was resolved through talking and meeting halfway.
In Chapter 32 of Miss Kobayashi's Dragon Maid: Elma's Office Lady Diary, Elma comes across two of her coworkers making out in secret, and a visiting Tohru ends up convincing her that the two are actually having an affair because of all the soap operas she's watched. They're actually a married couple. Tohru and Elma's confusion stemmed from the fact that the wife kept her maiden name for professional reasons.
Happens in My Bride is a Mermaid when a series of events results in Lunar's father walking in on Nagasumi rubbing Lunar's ass. Everyone immediately assumes that he was cheating on San, including San herself. Despite the fact that this exact circumstance (mermaid gets wet, reverts to mermaid form, forcing Nagasumi to dry them off, only for them to turn human at the worst possible time) has happened to her.
Naruto: Naruto Gaiden comes down to this. Sasuke's daughter Sarada worries that Sakura is not her biological mother, Karin is. She goes through a lot of trouble to find out the truth and even Naruto believes that maybe Karin is her mother. It turns out to be a misunderstanding. Sakura is Sarada's biological mother after all.
A variant occurs in Negima! Magister Negi Magi where Yuna Akashi finds out her father is seeing a woman that's not her mother. Yuna's friends point out that her mother is already deceased, so it's actually impossible for him to be cheating on his wife. Yuna herself is just jealous because she has rather complex and borderline unhealthy feelings for her father. As it turns out, her father and the other women are Just Friends.
One Piece: Played for Laughs for a brief moment: Vivi only decides to tag alongside Wapol because the World Government is after the both of them, but Wapol's wife misinterprets it as her husband eloping with a young woman.
One Planetes episode begins with Lavie seeing Fee talking to Director Dolf; as he's on a balcony a good distance away, he can't hear a word of it and assumes they have ulterior motives. (They're actually discussing Fee's possible promotion.) When he tells the rest of Debris Secton about this, they come to the en masse conclusion she's cheating on her husband. This lingers until Ai finally just asks Fee about it. Jump Cut to Lavie taking a roundhouse kick in the chest for having started the rumor. It doesn't help that, previous to their work at Technora, Fee and Dolf were coworkers at a small firm, and thus are still friendly to each other in private.
Surprisingly, Pokémon the Series: Ruby and Sapphire features an instance of this in one episode — May's father Norman and the local Nurse Joy are actually setting up a fireworks display celebrating Norman and Caroline's anniversary. The English dub censors the plot by making it seem like Caroline and Norman are fighting, instead of doubts of fidelity being implied.
In the chibi "Tenipuri Family" episodes of the The Prince of Tennis anime, Inui is mistaken for cheating by Oishi (his wife) when Ryoma tries on his mother's lipstick and later uses one of Inui's shirts to wipe it off, leaving a Lipstick Mark.
Happens multiple times to Ranma from Ranma ½, almost always in a way that goes far beyond mere lipstick on his collar. A few examples:
- Caught in bed with a girl snuggled up to him, both of them asleep (the girl slipped into his bed while he was asleep).
- Caught with a girl attached to him like a barnacle while both of them are naked (she snuck after him into the furo as a cat and glomped him).
- Caught shoving a girl down onto a table while grabbing one of her breasts and shouting "Now give it up!" (No, seriously, it really isn't what it looks like.)
- Ironically, the one time he did want to be Mistaken for Cheating in order to get out of a commitment, he used a very literal Lipstick Mark (which he applied himself in female form) and it was casually brushed off by the girl in question.
- The entire student body always jumps to the conclusion that Ranma is cheating on Akane.
  Girl #1: Don't just stand there, Akane.
  Akane: What do you mean?
  Girl #2: Ranma is making moves on another woman again.
Seton Academy: Join the Pack!: Ranka's unnamed father and Miki Hadano are stranded in a blizzard and forced to share body heat to survive. Unfortunately, after the blizzard passes and the father goes home, his wife sniffs him and detects Miki's scent. She automatically assumes he's been unfaithful and locks him out of the house.
In the manga version of Shaman King, Anna mistakes Yoh's new Oracle Bell as a pager that a girl gave him. It doesn't help his case that he had a long black hair on his clothes from Silva. In the game Power of Spirits, this is taken further when Meril, a girl Yoh had never met until this point, walks in and hugs him.
In Tamagotchi! Yume Kira Dream episode 40, Chukatchi, who is already married to Chinatchi, starts spending more time with Benitchi. The Tama-Friends keep seeing the two together, leading them to believe Chukatchi is cheating on Chinatchi with Benitchi. It turns out to be a bunch of coincidences that made them look like they were cheating, and Chukatchi is still in love with Chinatchi.
Season two of Tiger & Bunny has the odd Hero Buddy version where Golden Ryan thinks that his partner Blue Rose is plotting to partner up with Wild Tiger^note and tries to warn Tiger's partner Barnaby. Barnaby himself finds it hard to believe and knows Kotetsu and Karina wouldn't do that, but the entire thing is framed as Barnaby being told his partner is cheating on him with a younger girl. In actuality, Kotetsu and Karina were planning a meetup with a sick fan of Blue Rose, who turned out to be a Stalker with a Crush from the previous season.
Trapped in a Dating Sim: The World of Otome Games is Tough for Mobs: Several others walk in while Leon and Noelle are alone in a room, the former holding a chain attached to a collar around the latter's neck. Moreover, there's a baby carriage in the room. The collar was actually put on Noelle by someone else and the baby carriage was from Leon taking care of a classmate's sick dog, but the situation certainly looks like something particularly kinky.
Thanks to a misinterpreted conversation eavesdrop in a chapter of The Tyrant Falls in Love, Morinaga comes to believe that Souichi is having a sexual relationship with Isogai. (The truth is far more embarrassing for Souichi: he was blackmailed by Isogai, who discovered the relationship between him and Morinaga, into singing the Doraemon theme song on karaoke nights at Isogai's place.) One part that does not follow this trope is the discovery of hickeys on Souichi's neck which Morinaga takes as solid proof, forgetting that he made them himself several days ago.
Villager A Wants to Save the Villainess No Matter What!: Allen being seen carrying a small child, Millie, earns him glares and starts rumors that he had an affair and bastard. He's actually only carrying Millie because her life is bound to a Spirit of Light Allen needs to consult to treat his partner.
Shi from Wandering Son mistakes Yuki for cheating with one of the protagonists, Takatsuki, in his first appearance; she's touching him rather suggestively on the face. The creepy part is that, though Yuki would never harm Takatsuki, she is in her mid-twenties at youngest, and Takatsuki was only eleven... And though assigned female at birth feels that he's actually more like a boy, though neither Shi nor Yuki knew that (though Yuki seemed to have guessed).
In The World God Only Knows, Elsie passes herself off as an illegitimate daughter of Keima's father (who is constantly away on business), which leads to his mother angrily calling her husband up. Later on, Haqua does the exact same thing, which leads to another angry call to a now very confused husband getting yelled at about how many bastards he has.
Lampshaded in YuYu Hakusho, when Keiko misunderstands Yusuke's relationship with Botan, who is just a friend and a partner to the spirit detective.
Yusuke: Wait, Keiko! It's not what you think!
Keiko: How do you know what I'm thinking?
Yusuke: Because I know what it looks like!

Asian Animation

Pleasant Goat and Big Big Wolf: In Great War in the Bizarre World episode 52, a montage of Darton pulling pranks features him replacing a chicken's egg with a pelican's egg. When the egg hatches, the chicken's husband gets angry at her and chases her around.

Comic Books

Archie Comics:
- One story had Archie's mother borrow his jacket and accidentally leave a tube of lipstick in the pocket. Betty and Veronica later borrow Archie's jacket and find the lipstick. They think that Archie is seeing another girl because the lipstick isn't either of their brands and angrily confront the baffled Archie. Betty and Veronica both dump Archie, but then they realize that this will just make him go after the girl they think he's seeing now. They both come back and smooch Archie to show that they're better than the competition. The story ends with Archie's mother realizing what she did and apologizing if she caused him any trouble, but a love-dizzy Archie just tells her to cause as much of it as she wants.
- Another story had Betty crying her eyes out because her dad's business had gone under. Archie sees her and she runs up sobbing into his jacket. Veronica sees this and takes it as Archie cheating on her. Archie adamantly says "Oh, shut up, Veronica!" Which irks her to no end. Archie shows no remorse, and the act impresses even Reggie. It's when Veronica hears them talking about it that she learns of Betty's dad.
Batman: In one comic, Joker decides to mess with a rehabilitative Two-Face by suggesting that his girlfriend and best friend Bruce Wayne are fooling around behind his back and want to keep him locked up in Arkham. To give it one final push, Joker has one of his goons set up a mistaken newspaper article that Bruce and Two-Face's girlfriend were getting engaged, with use of a carefully-timed Not What It Looks Like photo, and lying to the reported. Then following it up by slipping it to an already suspicious Two-Face who loses it, escapes from Arkham, proceeds to kidnap his girlfriend, and attempt to murder Bruce.
Deadpool (2022): Issue 6 opens with Atelier assassins Drop and Rävhonna spying on Deadpool, who's sitting at a café table with a bouquet of flowers; they assume he's on a date with Valentine and plan on killing them both when the latter shows up. Instead, Lady Deathstrike appears, catching them both off-guard and causing Drop to assume that Deadpool is cheating on Valentine with her (which only makes him want to kill the Merc with a Mouth more). In truth, they’re meeting so that Deadpool can get her help with his and Valentine's upcoming date night.
Double Duck: Every time Daisy sees Donald with Kay K believes Donald is cheating on her. This naturally is followed by the use of I Can Explain and Blatant Lies.
The Flash: In The Flash (1959) #270-275, Barry Allen is mind-controlled by a woman called Melanie, who eventually managed to bring him to a motel where she made him remove his mask... and was then disappointed at how "ordinary" he looked and released him. By this time, Iris had become suspicious enough to put a tracking device in his costume, but when he explained the truth to her, she found it funny.
"Food for Thought! (1953)": Shortly after their wedding, Phil is bothered that Kadira rarely is home when he returns from work. He gets it in his head that she's seeing someone else. He complains and she makes sure to be at home for him, which puts him at ease until he discovers she's resorted to sneaking out in the middle of the night. He keeps quiet and follows her on her next outing, ready to kill her if his suspicions of infidelity are true. It seems they are when he observes her approaching a man, but they are proven to be incorrect when Kadira stabs the man and eats his arm.
Legion of Super-Heroes: In Legion of Super-Heroes (1980) issue #289, Light Lass looks for Timber Wolf and Saturn Girl -her boyfriend and sister-in-law, respectively- after they go missing during one mission. They're hugging each other when she finally finds them, and no matter how many times Timber Wolf explains he was trying to reassure Saturn Girl because she was severely upset, Light Lass doesn't fully believe him. During The Great Darkness Saga, six issues later, she still thinks Timber Wolf maybe cheated on her with her sister-in-law.
Manhunter: When Kate first shows up at Dylan's place his girlfriend sees her and immediately assumes Dylan is fooling around with her. While it seems Dylan has in fact been cheating on her this time he was innocent, but one of his supposed lovers showing up at home is too much for her and she leaves with their baby.
Robin: Tim gets forcefully kissed by a Stalker with a Crush and his girlfriend Stephanie sees it following a period of distance between them. She decides he's cheating on her and refuses to talk to him for a couple of months.
The Simpsons: One comic book story has Homer repeatedly moaning "Selma" in his sleep, which (along with a few other events) leads Marge to the improbable conclusion that Homer is cheating on her with her sister. At the end of the story, it's revealed that Homer has actually been dreaming about a pork festival in Selma, Massachusetts.
The Spectre: After dying and being resurrected as a corporeal ghost, Jim Corrigan broke up with his fianceé Clarice Winston without explaining why. Decades later, Clarice hired a private detective to find him, only to find a Jim Corrigan who looked exactly the same. Clarice concluded that not only was this her ex's son, he would have been conceived while they were in a relationship.
Spent:
- Alison becomes more and more riddled with worry that her partner Holly is attracted to Jeri, their veterinarian, because of their seemingly flirtatious repartée. Holly reassures her that it's just banter and that if Holly actually got attracted enough to someone else to want to do something about it, she'd never sneak around... she'd definitely tell Alison. This does not really reassure her. Later, Alison seemingly finds them in an intimate pose in the goat pen, but they're actually wrangling one of the goats to trim its hooves. Finally, when Alison is in LA to discuss the TV deal for her next book, Holly stops returning her texts or picking up the phone. Alison is frantic by the time she gets back home — only to find that everything is fine and that one of the goats has eaten Holly's cell phone (and there's a Shockingly Expensive Bill for the surgery to deal with it).
- JR and Badger see JR's parents Sparrow and Stuart each independently kissing Naomi and jump to the conclusion that both of them are cheating on the other. Actually, they're polyamorously dating Naomi together, and have been dithering about how to tell JR (who is themself polyamorous).
Spider-Man: Mary Jane Watson's Aunt Anna once tried to get her to face the "truth" about Peter Parker's apparent infidelity, what with all his sneaking around at odd hours and missing commitments with the flimsiest of excuses; this aggravated MJ enough to evoke a Sarcastic Confession: Her husband was really Spider-Man.
Shock SuspenStories:
- A story in #11 called "Three's a Crowd" had a paranoid man believing his wife was cheating on him with his brother and he murders them both. It turns out they were being secretive because they were planning a Surprise Party where the husband would find out she was pregnant.
- Another story in the same comic, "The Tryst," was based around a man being extremely possessive of his much younger Trophy Wife. When she mentions a new male friend, the husband believes she is having an affair and shoots her friend dead from a distance. The friend turns out to be a young orphan boy she had been caring for because her husband refused to have a child with her.
Superman:
- Superman had to deal with this in Action Comics #822 by Chuck Austen, when Lois discovered a pair of Lana Lang's panties in their bed which the jealous Lana had planted during her last visit.
- When Cir-El makes her first public appearance and introduces herself as "Superman's daughter", she leaves out some vital details to her story (that Lois Lane is her mother and she comes from the future) that cause Lois to mistake her for a lovechild born from Superman having a tryst with Wonder Woman.
- Jimmy Olsen has been known to be Disguised in Drag on more than one occasion. After one such example, though, Jimmy got read the riot act by Lucy Lane. Turns out Lucy found in his apartment the purse, perfume, and jewelry that were part of the masquerade lying around his apartment, but she thought he was dating someone else behind her back.
Supergirl:
- Supergirl (1972):
  - In issue #2, Linda — the eponymous heroine — is doing mouth-to-mouth resuscitation to a drowned man. One of her classmates who flirts with her earlier meets them and thinks she is cheating on him... even though she is dating nobody.
  - In issue #6, Supergirl is hugging gang leader Ricky in gratitude for listening to her when Loretta — Ricky's girlfriend — walks in on them and thinks her boyfriend is cheating on her with Supergirl. However, it was a totally innocent act.
- In Supergirl (2005) story arc Girl Power, Cassie Sandsmark walks in while Kara and Superboy are having an argument and assumes that the two are engaging in foreplay. She attacks Supergirl and loses, but the misunderstanding is cleared up.
  Supergirl: Whatever you thought was going on, Cassie— wasn't. I came looking for someone I could talk to.
The Transformers: More than Meets the Eye: Implied when Rewind approaches his husband Chromedome's good friend Brainstorm asking him where Chromedome is, and mentions that Chromedome has been saying Brainstorm's name in his sleep. Brainstorm completely misses the point, and assumes Rewind thinks that he and Chromedome are working on a super-secret project together. (Rewind's response: "Er, I didn't until you said that.") As it turns out, that's exactly what they've been doing, although Chromedome keeping the very grave nature of the project a secret ends up having repercussions on his and Rewind's relationship regardless.
Ultimate Spider-Man (2000): Liz is drunk at a party at Kong's house, and tries to make the moves on Peter. He tries to get her away from him, but Mary Jane shows up just in time to see a passed-out Liz lying on top of Peter. Never mind they weren't actually dating at this point. Peter tries to chase after her to explain, only to run into a worse problem: His uncle.

Comic Strips

A series of FoxTrot strips has Andy convinced that Roger is cheating on her when he's actually at work. ("Listen — hear that squeaking? You know how my chair squeaks." "Sounds like bedsprings." "Fred, get in here and talk to my wife.") In the last strip, she apologizes for being paranoid and they hug... at which point she plucks a hair from his jacket and asks whose it is. (No, Roger wasn't cheating; he's just balding.) Fred's response to being called over is "Not again...", implying that Andy does this with some degree of regularity.
One comic in Andy Capp has Andy returning home late and apologizing to his wife. He comments that she hasn't said anything for three nights, and jumps straight into assuming the worst.
Andy: WHO IS HE?
For Better or for Worse: After days of dealing with the birth of April and his freeloading cousin Fiona, a stressed out John declares to his staff that he’s getting "an apartment". What he means is that he’s kicking Fiona out of the house and getting her a new place to live, but the staff believe that John is leaving Elly and cheating on her with Fiona. However, they never confront anyone directly, instead driving to the apartment building and watching John move Fiona in, calling Elly to tell her they’re sorry, and giving John dirty looks. It’s never revealed if John and Elly ever learn about the mix up.

Fan Works

Adventures of a Line Hopper: This problem shows up multiple times in the alternate universe where the Doctor is Buffy's "boyfriendish".
- Ship Time has the Doctor refusing to see Buffy every night for two weeks, ostensibly to spend time with the TARDIS, but really to fill in Buffy's job with Giles' help so Buffy can focus on her final exam. Buffy gets suspicious and the Orb of Uerzeno channels the suspicion to create an illusion of the Doctor actually making out with other women, which only stops once Giles talks to her and clarifies things including about the orb.
- The Buffybot/Spike situation happens in The Years that Never Were as in the main universe, except here it also makes it look like Buffy is cheating on the Doctor with Spike. Fortunately, it gets solved pretty quickly since the moment the Scoobies tell Buffy and the Doctor about their suspicion, Buffybot immediately walks into the room.
Family Guy Fanon:
- Season 3's "A Cheater Runs Through It" has Lois thinking Peter's cheating on her overseas due to him being suspicious and spending more time on his boat than with his family. The real reason was that Peter was rearranging his boat to host a wedding for Randall Fargus and his new wife Eliza and was secretive because Fargus wanted to keep it on the down low.
- Season 21's "How I Met Your Real Father" has Stan Thompson reveal to Meg that his accidental pregnancy to Lois that resulted in her birth lead to Stan's wife thinking this. However, compared to the above example, she kicked him out of their house without giving him so much of an explanation, effectively divorced him.
In An Affair or Something:
- Ruby mistakenly believes that Jaune is cheating on her with Pyrrha. While Pyrrha does desire a relationship with Jaune, and is silently hoping Ruby and Jaune's marriage ends with divorce as result, their interactions never went beyond friendship, with her mainly acting as a pillar of support after his attempted suicide.
- Jaune believes that Ruby cheated one him at least twice with one of her acquaintances to conceive their children and has started to do so again. Ruby had never been with anyone else. She'd gotten pregnant through secretly visiting sperm donation clinics in an attempt to spare Jaune’s feelings about his infertility, assuming that he didn’t know about it (having secretly gotten him tested). The resemblance that their daughters have to Cardin is pure coincidence.
The Choices We Make: When Blake hears the story of how a cat faunus woman named Kali kissed Jaune during his travels, she immediately assumes that it was her mother. Since no one knows that the woman was Sienna using an alias, Blake's horrified and begins to silently hate Jaune for seducing a married woman.
had i not been made of common clay: The infamous adultery from Arthurian legend is subverted. Arthur and Guinevere are very much in love and Happily Married. But between cultural standards frowning on public displays of affection, combined with Arthur being intensely private and The Stoic even by that standard, most people never see them showing real affection. Then when Guinevere starts spending an unseemly amount of time with Lancelot (mostly to complain about Arthur sacrificing his happiness for the sake of the country), rumors start spreading. The fact that everyone except Arthur and Guinevere can tell that Lancelot is in love with Guinevere doesn't help. After Agravain finds out that Arthur is a woman, his misogyny rises and he doesn't even consider that the two might be in a real, loving relationship. He assumes Guinevere is having an affair, and blackmails her by threatening to reveal Arthur's real gender. Guinevere "confesses" to adultery when he publicly accuses her, to Lancelot's shock and horror. It's unclear if Arthur ever finds out that it was a false confession, but he officially pardons both of them anyway. Unfortunately, by then it's too little, too late.
In Your Wildest Dreams:
- Yang often jokingly accuses Jaune about cheating on her because she finds the very idea he'd ever do such a thing amusing. She mostly pulls this with his friendship with Blake, due to their antics making for easy fodder (one notable instance being when Blake admits that she was staying up late waiting for Jaune to leave his room when asked how she knew Jaune needed help) and Blake continuing to be flustered by such jokes long after Jaune himself has developed an immunity to them.
- Likewise played for laughs when Jaune tells the rest of his team between chapters about having encountered Trivia in the locker room, and being gifted her necklace and bra. While he's happy that they quickly figured out the real reason for the gifts (the former to verify to a third party that she's alive and well, the latter for shits and giggles), he's also a bit offended that they didn't even entertain the possibility that it was a sexual encounter.
  Though it was a little insulting to have them discard the possibility so quickly. Like, he hadn't, but he could have. Maybe. It was a possibility, okay? They didn't have to look like the idea was so unlikely!
Kingdom Hearts: The Antipode: Played for Laughs during the fourth installment's Olympus Arc. Zeus sees Hercules with Aqua and assumes that the former is cheating on his love interest Megara. Not that Zeus sees anything wrong with it.
Hercules: [Groan] Father, I'm not two-timing!
Zeus: Of course not! No son of mine only settles for two!
Requiem for a Loud has Lincoln trying to tell Ronnie Anne the truth about his condition. He's almost close when Cristina comes in. In that moment, RA thinks that he is getting together with Cristina when he isn't. It is soon resolved.
In The Amazing Spider-Man: True Purpose, when the new Unity Squad see Spider-Man come downstairs while they're having breakfast in the mansion, the web-slinger closely followed by Black Cat in a manner that makes it clear they spent the night together, certain parties assume Peter’s cheating on Mary Jane/Red Sonja, before the redhead in question appears after the other two and clarifies that they were actually enjoying a weekend-long threesome.
A Pikachu in Love has an odd platonic, 'best friend' version. When Ash wakes up the morning after Pikachu spent the entire night up with Pichi, he's confused as to why his friend is still sleeping when he's usually up at this hour. Deciding not to disturb him he takes Bayleef fishing with him instead. Unfortunately, Pikachu wakes up a few seconds before they leave, and wonders why Ash didn't take him instead. This is what gets Pikachu to really consider how strong of a bond with Ash he actually has...
In A Vow Eternal series, the fic "On the Precipice" opens with Mariner walking into the bar to see Boimler apparently kissing a new ensign he's been mentoring, but she leaves too quickly to see Boimler push the ensign away and make it clear that he's committed to Mariner. Mariner spends the next week in a blind rage towards even the topic of Boimler, until Tendi and Rutherford are able to show her security footage confirming that Boimler didn't do anything.
Evangelion 303: When Mandy perused her girlfriend's Secret Diary she read many entries where Jessika revealed that she had a crush on her teammate Asuka and described what kind of things she wanted to do with -and to- the red-headed girl. Mandy thought Jessika had been unfaithful and she even accused Asuka from being a home-wrecker, but Jessika never cheated, and those diary entries were merely her fantasies.
Higher Learning (Strike-Fiss): After partially overhearing a conversation between Asuka and their teacher where he apologises for overstepping his boundaries and she replies it was not his fault, Shinji thinks Asuka is cheating on him. In reality, nothing happened between them.
My Immortal: When Ebony sees Draco (her boyfriend) with a tattoo that reads, "Vampire" (Harry Potter's nickname), she thinks he's been seeing Vampire. Oddly enough, she accuses Vampire of cheating on her. In actuality, they had been in a previous relationship but Vampire left Draco for a girl named Britney before Draco got together with Ebony.
In this Smallville fanfic, Lex Luthor is caught "cheating" on Clark Kent with Superman, mixing Mistaken for Cheating with Two-Person Love Triangle in a PR disaster.
In Through a Diamond Sky, this kicks off the plot. Jordan thinks that Kevin's secretive behavior, bizarre references, and long periods of no accountability are proof she's married a cheater - again. (He's husband #2). While it's true that he's up to a lot of very strange things in cyberspace, an affair isn't one of them.
In the Total Drama fanfic, Total Drama Legends, Mike repeatedly mistakes Zoey assisting or comforting Duncan during his emotional problems as the two seeing each other behind Mike's back.
In the Ben 10 Hero High: Sphinx Academy, Ren suspects this of Ben when she has noticed him hanging out with Julie several times, though more often than not he is getting help from Julie to get a gift for Ren for their upcoming anniversary. It doesn't help that Susan, one of the Big Bad's lackeys and instructed to cause tension between the couple to slow them down, is the one encouraging the idea.
In The Lunar Rebellion, Nimbus Kicker thinks her lover Radiant Day is cheating on her with another mare. Turns out, White Knight is Radiant's sister. She's also his squire. But more importantly, she's his sister.
In The Many Secret Origins of Scootaloo, Mrs. Cake catches Fluttershy giving Twilight Sparkle mouth-to-mouth, and immediately spreads the word that Twilight is cheating on Rainbow Dash. Twilight and Rainbow Dash aren't even dating.
The Reading Rainbowverse has a... complicated example, in that Big Mac thought he'd made it clear that he'd broken up with Fluttershy, but Fluttershy didn't get the memo, and the fact that Mac was interested in a relationship with a changeling of all things just made the situation more awkward. It ended up with Fluttershy going on a drunken rant and then getting suplexed off a dragon, after which she spent a couple weeks in the hospital high on morphine...
Pops up from time to time in Miraculous Ladybug fanfiction with the complication of the series' Love Square: i.e., one of the heroes will be suspected of cheating on their partner with... their partner.
- In the post-reveal fic Glaze, Alya figures out from a few clues that Adrien and Chat Noir are one and the same, and her immediate reaction is to call him a lying cheating asshole for kissing Ladybug behind Marinette's back. It takes her a minute (and Marinette walking in, hearing her accusation and addressing Adrien as Chat) to realise that Marinette is Ladybug.
- The fic Odds Are That We Will Probably Be Alright, is set in a future where Marinette and Adrien have been dating since high school and are engaged to be married. However, both have become convinced the other is cheating on them, due to frequent suspicious disappearances and flimsy excuses, but neither of them can say anything to the other without risking their own secret, forcing them to confide in their respective best friends and their partners. When Nino and Alya get tired of their complaining, they force them to confront each other about it, leading to a heated argument where both become angry at the other's accusations. It gets to the point where Adrien decides to clear himself by admitting to being Chat Noir... but his wording — "I'm fucking Chat Noir, okay? That's why I have to leave." — predictably has the exact opposite effect, getting Marinette, Alya, and Nino furious at him until he transforms to show them the truth.
  Alya: I can't believe we had to spend months with you two thinking you were cheating on each other with each other.
  Nino: Not with each other. Adrien did say he's been cheating on Marinette with himself.
- Another post-reveal story, Scandalous! has Alya walking in on Marinette kissing Chat Noir, followed a few days later by Nino catching Ladybug kissing Adrien. Fearing that her friends' relationship is falling apart, Alya brings them together for an intervention. However, Adrien and Marinette manage to come up with the excuse that they had a bet about who could kiss their favourite superhero first — Marinette won, but she said that Adrien could go through with the kiss if he ever got the chance. Alya almost buys it, only to instead start to suspect that her friends are Ladybug and Chat Noir.
- Played more seriously in Back To Us. Alya comes to suspect something's going on with Nino and Marinette after overhearing and misinterpreting a conversation between keeping their superhero lives from her, leading her to break up with Nino right when he was about to propose. She figures out the truth before too long and they get back together. Earlier, the host of the Christmas Ball is akumatized because he believes his supermodel wife is unfaithful, having a lot of private meetings with other men, including Adrien. In reality, she was cancelling arrangements so that she could quit modeling and dedicate her time to their coming baby.
- I Saw Mummy Kiss Chat Noir features an Adrien and Marinette who are Happily Married with three wonderful kids and another on the way. Unfortunately, the eldest of their kids, one Emma Agreste, sneaks out of bed one night and sees her mother kissing Chat Noir. Cue Adrien and Marinette wondering why their daughter suddenly and violently loathes all things Chat Noir. The fic ends with the younger Agrestes walking in on Adrien kissing Ladybug.
- A variant is present in The Seven Misfortunes of Lady Fortune. Alya is actually happy that Adrien spent the night with a girl instead of wallowing in memories of the long-dead Marinette... but goes absolutely berserk upon hearing a noise from upstairs, and realizing the two must have been defiling the late girl's bed. Later, during a school reunion, she enters her old class and sees Adrien making out with a girl sitting on her late friend's table. Just as she's about to murder them both, the girl turns her face toward Alya...
- Hero Chat: Lila sees Marinette on a date with Luka, and takes a picture to gleefully show to Adrien that Marinette is cheating on him. Adrien just says "yes, that is my girlfriend with our boyfriend." For bonus points, Adrien and Kagami (the other part of the polycule) were apparently sitting at the table with them, but since they were wearing hats and sunglasses Lila didn't recognize them.
- A non-Love Square related example occurs in Reverstrator; angry that the two of them don't believe her lies, Lila photoshops pictures of Nathaniel and Marc to make it seem like they're cheating on each other with Alix and Adrien, respectively, and sticks the photos in their lockers. While they're initially heartbroken, they manage to talk it out and realize what happened...and unfortunately for Lila, this reconciliation happens while they're akumatized, and they immediately go for her blood.
- Discussed in the post-reveal fic Divergent Points - Weredad, where Marinette's parents find her in her room kissing Chat and conclude that he is her boyfriend. Afterwards, Marinette points out to Adrien, Alya, and Nino that they can't be together as both civilians or as both heroes because it will be seen as Marinette and Chat cheating on each other. Luckily, Alya comes up with a good cover story to share with Marinette's parents and avoid this issue: Tell them that Marinette, Adrien, Ladybug, and Chat Noir are in a Polyamory relationship.
- The Princess Is Not in Another Castle; This One Is Safe Enough: As far as the public is aware, Marinette is dating Adrien. In an effort to ruin Marinette's reputation, Lila films a clip of her kissing Kagami then tries to expose it to the whole class. Adrien tells their classmates that was not cheating... because he isn't dating Marinette. Kagami is the one dating her and he's been The Beard to help hide their relationship from Kagami's controlling mother. The rest of the class understands and supports the girls' relationship, then turns on Lila for trying to force Marinette out of the closet. The end of the story reveals that Marinette, Adrien, and Kagami are actually in a polycule. Adrien had said that only the two were dating partially out of panic trying to counter Lila and partially because he didn't want their unusual relationship exposed to the public, where the paparazzi would dissect it for their own entertainment and his father would try to exploit it for his own benefit.
Done very bleakly in The Keys Stand Alone: The Soft World when Paul finally confesses to the others that after he came home from C'hou in With Strings Attached, he had a tough time adjusting to being normal again, and for a while was terrified to even touch Linda and his kids. She decided he'd disappeared for those four days with another woman and now hated her. Given that the truth was, as Paul put it, "so fucking insane," it took him quite a while to both get over the sense that he would kill her if he hugged her and to convince her of the truth.
In A Complete Turnabout Phoenix gets a pink letter from Maya leading to the belief that he's cheating on Iris. The letter wasn't a Love Letter and it was pink because of Maya being Maya. Ironically Iris herself doesn't seem to care about the letter.
In Supergirl (2015)/The Flash (2014) crossover Call Me Kara, Kara and Barry's first fight occurs when she walks in on him and Iris hugging after sharing lunch. Of course, she was already upset, given that that day was the anniversary of her planet exploding.
In the Teenage Mutant Ninja Turtles (2012) fic "So Much for the Impossible", when April reveals that she's pregnant, despite her having been in a relationship with Donatello for the past year, Donatello, Splinter, the other Turtles and Karai all immediately assume that she cheated on Donatello before she affirms that he's the only person she's ever been with. Once the misunderstandings have been cleared up, all parties are swift to apologise for assuming the worst, although Donatello is left to have an awkward talk with Splinter about "protection".
In Persona EG, Sunset Shimmer pins Flash Sentry against a wall and forces a deep kiss on him in front of Twilight, reducing her to tears. Turns out someone took a picture of the kiss and posted it to Canterbook, and by the end of the day everyone has seen it and thinks Flash is cheating on Twilight with Sunset, even his friends. Luckily he is able to clear everything with them by sitting down and talking to them, saying she assaulted him and she was the one who kissed him.
In The Power of Seven, many characters, on realizing that Harry is getting close to, flirting with, or having sex with the other six girls, assume he is cheating on poor Ginny. Ginny has to explain "We have an arrangement" (Harry needs to spiritually bond with seven witches to destroy the horcrux within him and Ginny has realised that she likes to watch Harry with other girls), and even that doesn't always work. Some assume that she's so blinded by her desperate Hero Worship of Harry that she'd let him get away with anything in exchange for him giving her a fraction of his time and attention.
In the Pokémon the Series fic "The Beginning of a New End", while Ash and Misty aren’t dating at the time it happens, they experience an equivalent such moment when the two are on a new journey through Kanto after Ash won the Hoenn League. At one point, Ash leaves Misty in Saffron City while he allegedly goes off into the woods for a training session with Pikachu. However, when Ash is talking to Misty on a vid-phone and May appears behind him, Misty assumes that this means Ash left her in Saffron City- a place she still has nightmares about- just to visit May in Johto. Fortunately, Ash is able to get back to Misty in time to explain that he was just in Johto to capture a Tentacool for Misty for her birthday, and May’s presence at the same time was a complete coincidence.
Prodigal Son: When Astrid and Fishlegs start collaborating on figuring out the nature of Hiccup's absence, her mother starts to suspect that they are having affair.
In Tony's Girl, Laura Barton accuses Clint of having an affair with Wanda, because why else would he come out of retirement and abandon his family to help a former HYDRA agent if he wasn't fucking her.
Invoked in The Ripple Effect in order to get Jerrica to run to Riot. At Jerrica and Rio's wedding, Minx drugs Rio, takes him into a room and makes it look like they slept together. Jerrica catches them and gets the wrong idea. Luckily, Stormer noticed what Minx did and spoiled The Stinger's plot.
Máscara Sonreindo: When Kagami tells Misao that Ayano has a boyfriend, Misao thinks that Ayano is cheating on her. In reality, Ayano just made up a boyfriend to stop boys from hitting on her.
Of arcane energy and missing hearts is a rather intricate one. In the fanfic, Taako's soul is switched with Damian, a tiefling. As such, his soul is now in a different body. Once Kravitz figures it out, he immediately kisses Taako after Damian (in Taako's body) is knocked out. Of course, this is at the moment when Lup comes in, and finds her "brother" out cold with his boyfriend making out with a total stranger. She almost burns the two to ash before her real brother talks sense to her.
Played for Drama in Flowers Drenched in Vodka. A drunken Eli reacts so negatively to seeing Umi exit her house that she beats her girlfriend Hanayo so hard that she gets sent to the hospital.
In Lady and the Tramp III: Family Troubles, Lady gets suspicious of her husband Tramp when his old fling Peg reunites with him. She sees Tramp sneak out one night and smells Peg on him when he comes home the next morning. Despite Tramp insisting that they just talked, Lady doesn't believe him. When he runs after their runaway son Scamp, Lady worries that Tramp plans on leaving town with Peg.
Roadside Assistance: Yang sees Neptune kissing Sun and is enraged that he's cheating on his wife Weiss. She doesn't know that Weiss encourages Neptune to date because their relationship isn't romantic^noteThey're both gay.
In the old (NSFW) fic With Three You Get Eggroll, Hermione mentions almost killing Lupin the first time she caught him and Tonks spicing up their love life the obvious way.
Restraint: Invoked. Azula lied to Ty Lee and stated that she cheated with Katara. She keeps up the lie for years because it's easier than explaining the truth.
In The Loud House fanfic Boys and Girls, Lori thinks Lincoln is dating Ronnie Anne when he's in a suit, claiming he's going to go to a fancy restaurant, but not with Ronnie Anne. Really, he's pretending that he's going out with Hugh.
An understandable mistake in Young Justice fanfic With This Ring; Superboy and Miss Martian are dating, as per canon, but unlike canon, he is adopted by Wonder Woman. Who, in addition to being a highly attractive woman, is basically ageless, and therefore doesn't look old enough to be his mother when kissing him on the cheek before school.
Tyrantly Ever After: In order to figure out some way to help his lord keep the promise he made to Artina, Fenrich begins meeting with the angel regularly in her quarters. A prinny notices him making his way to her door and comments on how he's seemingly "two-timing your boyfriend with his girlfriend" in an approving fashion. Fenrich promptly chucks him out a window.
In My Wish Order Brother, Ino comes to believe that Deidara and Naruto are her half brothers fathered by Inoichi due to misinterpreting a conversation with her mother, and continues to believe this due to her mother forgetting to correct her. Eventually, this belief spreads to all of Konoha and everyone believes Inoichi cheated on his wife.
The Fate/stay night fan-video How Do You Sleep? has this Played for Drama. Shirou and Saber are in a relationship, but Shirou finds that Saber has been receiving texts from other guys like Diarmuid and Gilgamesh. Fearing that she is cheating on him, he falls into despair and ends up having affairs with other partners as a result. As Saber has no idea why he is acting this way, she becomes heartbroken by his cheating and ends up leaving and moving in with Diarmuid. It's not until after Saber leaves that Shirou receives a furious text from Gilgamesh, revealing that she never cheated on Shirou with him or anyone else. Shirou ends up devastated that his paranoia had pushed away the woman he loved.
Subverted in the House/Once Upon a Time (2011) fanfic Definitely not Lupus. When everyone finds out that Emma is pregnant, Chase attempts to claim that Emma didn't tell Regina because she obliviously cheated on her. Regina doesn't buy into it for a second and instead simply punches Chase for even suggesting it.
A darker take on this trope in The Remarried Empress fanfic All that glitters is not gold, where Heinly shows his crush Navier pictures of her husband Soveishu seemingly having an affair with a woman named Rashta. While Navier is shocked to see the picture, that's because she and Soveishu are Serial Killers and Rashta was Soveishu's target at the time. The couple decide to kill Heinly and Make It Look Like an Accident to make sure he doesn't find out about their true activities.
In the SPY×FAMILY fanfic Operation: Adultery, Loid suspects that Yor's, his Marriage of Convenience partner, frequent disappearance and constantly covering herself in perfume is because she is having an affair, unaware that she moonlights as an assassin. In this case, Loid suspects that someone has been forcing Yor to do this against her will, and he claims he is only trying to stop it because it is a threat to his long-term mission and not because he's upset that Yor is seeing someone else.
In some Good Omens (2019) fanfics where Crowley is gender-fluid ^noteNot much of an exaggeration of canon; Crowley is canonically Non-Human Non-Binary, generally presents as male, but sometimes presents female, his husband/boyfriend Aziraphale referring to him as his current presentation leads to Aziraphale being mistaken for unfaithful.
- In The Official Mr Fell Quarantine Thread, a group of bloggers notice that Mr. Fell sometimes mentions his wife, other times mentions his husband, and is often seen smitten with a man nicknamed "Sunglasses". Theories abound that his wife is The Beard, they're in a poly relationship, etc. until one of them notices a woman with "Sunglasses's" tattoo, sunglasses, and fashion sense flirting with Mr. Fell.
- In Aziraphale Confuses His Wedding Planner, Aziraphale meets with his wedding planner once every few months, and refers to his (currently absent) fianceé by a different gender each time. The planner suspects that Mr. Fell is repeatedly breaking up with and finding new lovers, until Crowley shows up and clarifies that it's only been him from the start.
In the Supernatural/Dream SMP crossover The Secret to an Empire, Sam stumbles across Quackity acting intimate towards Sapnap and Karl individually at different points in time. As in Dream SMP canon, the three of them are in a polyamorous relationship — however, Sam doesn't find this out until he tries to tell Karl that Quackity is cheating on him.
"Bro really said, 'Yeah, your husband is cheating on you with your other husband, hope this helps.'"
The premise of wasting beats of this heart of mine is that Zagreus reincarnates as a mortal to escape the Underworld, and adopted by Philomenus the farmer. All his life, Zagreus was assumed to be Philomenus's bastard, which wasn't helped by how he shares his foster siblings' green eyes but not their light hair, and also how Philomenus told them about how he found Zagreus floating in a magical river. Zagreus mentions that he wasn't close to his foster mother because of that.
In The Shower Slip, Arthur discovers brown hair when cleaning out the shower drain. All the Weasleys, of course, are redheads and there have been no brown-haired houseguests using the shower recently. This leads Arthur to think Molly's having an affair. The hair belongs to Peter Pettigrew, aka Scabbers the rat. As in canon, they're unknowingly hosting him in his rat form, but in this fic he's apparently more finicky about his hygiene and less careful about leaving evidence around.
Yu-Gi-Oh! Arc V: Pendulum's Fifth Swing: Due to the number of Identical Strangers popping up, Yuya and Shuzo start theorizing that Yuya's dad and Shuzo's wife were cheating. In reality, all the identical stranger are either Alternate Selves or reincarnations, so (to our knowledge) there is no cheating involved.
In Dragon Ball's Tough to Swallow where Mr. Satan, to maintain his Fake Ultimate Hero status, starts inviting Goku for meals but soon starts asking Goku to train him. Due to a series of events, a photographer manages to snap several photos in Mr. Satan's bedroom where it appears that Goku and Mr. Satan are having a steamy affair. When it's made public, Chi Chi unfortunately believes it and runs to confront Mr. Satan ... where she sees Mr. Satan and Goku half-naked at the beach (they were having a training session).
Played for laughs in the My Hero Academia fic Love For All (NSFW). Izuku tries to explain to Tenya that he's in a polyamorous relationship with Ochaco and Tsuyu, but Tenya overreacts before he can explain the "polyamorous" part, dragging Izuku inside and forcing him to confess to two-timing the girls in question. Izuku proceeds to have a lot of fun with this "confession", with Tsu and then Ochaco playing along by feigning shock about the other two's relationship.
Tsu: [to Ochaco] Kero, how could you!? You’re dating Izu while also dating me?
Tenya: [blinking like a fish] W-Wha…
Ochaco: Gasp! You’re dating me and Deku, while I was dating you and him?! Oh the irony!
Izuku: [barely Holding in Laughter] Wait! While I was dating both of you, both of you were dating each other?
The Amphibia/The Owl House crossover "Guardian Angel" features Anne, Sasha, and Marcy all in a polyamorous relationship, but Luz doesn't realize this and comes to believe there's a three-way cheating scenario going on. She's quite embarrassed when she eventually realizes what's really going on.
In The Accidental Warlord and His Pack, once Jaskier, Geralt, and Eskel all get together, virtually every visiting noble at some point will see Jaskier and Eskel canoodling and assume to their horror that Jaskier is cheating on Geralt, with who knows what kind of bloody consequences should it be discovered. Someone more familiar with the situation will reassure them, and they'll still be bewildered at the idea of a consensual gay triad but less worried about the fallout.
Violence is not the Answer: Draco believes Harley is cheating on him after a Daily Prophet article includes a photo of Harley with Victor Krum's arm around her shoulders. He doesn't give her a chance to explain and breaks up with her.

Films — Animation

The plot of Corpse Bride twists this trope around a bit when Victor is spotted vanishing into the night with Emily (i.e., getting spirited away to the Land of the Dead against his will) on the eve of his Arranged Marriage to Victoria, while Emily comes to view herself as the one being cheated on when Victor tries returning to his rightful fiancée. Incidentally, Victoria is the only person who realizes there isn't any affair, but not a soul will believe her ramblings of Victor being kidnapped by a walking, talking corpse. In the end, the scandal is dropped after Victoria is pushed into a marriage with Lord Barkis, while news of the marriage persuades Victor to settle for Emily, who calls the whole thing off and helps Victor get back with Victoria upon recognizing herself as the third wheel from the start.
The Incredibles 1: Helen finds a strand of Mirage's hair on Bob's suit, then overhears the second half of their phone conversation before he suddenly leaves on a "business trip." It's never explicitly mentioned, but her thoughts are pretty clear. The outtakes, meanwhile, include scenes where she outright asked him if he was seeing another woman. To make matters worse, when she does finally find Bob inside the villain's lair, it's right as he's hugging Mirage (just out of pure gratefulness for helping him, but Helen doesn't know this). Helen promptly punches Mirage out cold.
In The Man Called Flintstone, Fred is forced to substitute for Secret Agent Rock Slag when the latter is incapacitated by the Green Goose's henchmen, Ali and Bobo. Fred is assigned to stall Tanya Malachite, another agent of the Green Goose until the real Slag arrives from his recovery, and when Fred's family and friends see him dancing with Tanya, they think that he is cheating on Wilma. When the real Slag arrives to take Fred's place, Fred's family and friends mistake him for Fred and knock him out, forcing Fred to take Slag's place longer than he had planned.
Monsters, Inc. 1: Due to a snafu in the restaurant where Mike accidentally said Sulley's name when about to call his girlfriend Celia beautiful, she thinks Mike is cheating on her with Sulley.
Open Season: In the sequel, Elliot mentions "that whole incident with the other woman", referring to Mr. Weenie's owner intercepting Elliot and Giselle's wedding. Everyone else thinks that he's confessing to having cheated on Giselle.
Elliot: "No, not that kind of other woman!"
SPY×FAMILY CODE: White: Yor thinks Loid is cheating on her after seeing him talking to an unknown woman and seemingly kissing her. It was Fiona in disguise and they were talking about WISE business. The "kiss" was Loid just stepping forward to catch Fiona's hat from blowing away in the wind. The angle Yor saw things from made it look like an intimate act. It doesn't help that her coworkers told her that if a man starts traveling more, changing his clothing style, and gives spontaneous gifts (all of which Loid does over the course of the movie), that's a sure sign he's cheating.
Strange Magic plays with this — one of the first scenes is of a fairy princess catching man she was about to marry kissing another woman (on their wedding day), but another character later describes the situation as a "misunderstanding" — her charismatic ex convinced everyone, including her father, that either he didn't really cheat or it was a minor lapse in judgment and won't be repeated.

Films — Live-Action

In American Dreamer, after Alan brings a wet and drunk "Rebecca" to his room, his date sees them together and then storms off.
Invoked in Andhadhun. Simi sets it up so that Sofie will believe that Akash is sleeping with Simi by poisoning him and opening the door partially undressed when Sofie turns up at Akash's place.
In The Big Clock, Earl Janoth sees George Stroud leaving the apartment of his mistress Pauline York and assumes that he is her lover. This leads to the argument in which he murders her. However, George had actually been visiting Pauline because she was attempting to persuade him to join her in a plan to blackmail Janoth. (And George had turned her down.)
In Big Fish, when Will meets Jenny, he rather abruptly blurts out the question of whether she and his father, Edward, had an affair. (Answer: no, but not for lack of her trying.)
The Birdcage: At the beginning of the movie Albert is convinced that Armand is having an affair because Albert found a bottle of white wine in the fridge and they only drink red. Armand also sends their housekeeper away so he can have the apartment to himself while Albert's working. A younger man shows up at the apartment and greets Armand with a hug, making it look like they really are having an affair. It isn't until Val calls him "Pop" that we learn he's actually Armand's son who just wanted to tell his dad he's engaged without Albert making a scene.
Blue Jean: Viv thinks briefly that Jean was having sex with Lois while in a bathroom stall together, leaving angrily before Jean clears things up.
Bridget Jones: The Edge of Reason was made up of this from poor communication. Bridget becomes paranoid that her boyfriend Mark Darcy and his younger, thinner, and composed Brainy Brunette assistant Rebecca were having an affair, and during Bridget's stint in a Thai prison he is revealed to think she got back together with his ex-friend Daniel. The couple gets back together in the end.
In The Bull of the West, Ben Justin, after some goading from a rival rancher, misinterprets his wife Mary secretly taking their son Will to the Shiloh ranch for riding lessons as her having an affair with the ranch foreman.
The Count of Monte Cristo (2002): After Edmond Dantes escapes from Chateau d'If, he returns to Marseilles, where he learns from his former employer, Monsieur Morrell, that his former fiancée, Mercedes, married Fernand Mondego only one month after his arrest. Led to think that Mercedes never loved him, he includes her in his targets for vengeance, though as they finally meet again, she shows him the makeshift engagement ring that she made before his arrest, proving that that she was always in love with Edmond, and it's later explained that the real reason she married Fernand so soon is that she had become pregnant with Edmond's son, Albert, and wanted the child to have a father.
The Dawn Rider: John arrives at the ranch soon after Rudd leaves but doesn't say any more to Alice than he needs to talk to Rudd. Ben arrives, sees Alice pleading with John, assumes the worst and leaves.
Deep Impact: This is how the story of the comet ends up breaking. The Secretary of the Treasury suddenly resigns, citing his wife having fallen ill and wanting to spend more time with her. This is correctly discovered to be a cover story, but his secretary misinterprets a secret phone call between him and the president to be about a mistress named "Ellie" and assumes the real reason he resigned was to avoid the fallout of an affair scandal. She's wrong, the phone call with the president wasn't talking about someone named Ellie, they were talking about ELE, Extinction-Level Event, and the actual real reason he resigned was because he wanted to be with his family before the comet's impact wipes out life on Earth within a year (as he didn't believe the mission to stop the comet would succeed).
Derailed (2002): When Madeline discovers Galina in the bathroom of Jacques' cabin, she assumes Jacques is cheating on her and that Galina is an escort
In the Soviet comedy The Diamond Arm, a man named Semyon accidentally gets an orthopedic cast full of diamonds placed on his arm during a trip to Istanbul by smugglers working with The Mafiya, assuming him to be a courier. Upon arrival back home, he immediately goes to the police, only for them to use him as bait for the larger organization. His wife starts getting suspicious about strange absences and a gun she finds in his things, but he tells her he is on a "special mission". It gets worse when their apartment building superintendent tells her that her husband's behavior is shameful, pointing out that she wouldn't be surprised if he's seeing another woman on the side (in the original script, she suggested that he might be secretly Jewish, but the line was overdubbed in post-production due to the Censorship Bureau). The bad guys hire an attractive blonde to seduce Semyon and put a sleeping pill in his drink. Just then, Semyon's wife (who has found the woman's note with her address) and superintendent burst in and see Semyon seemingly drunk (he's actually suffering the effects of the pill) with a half-naked woman dancing for him. The blonde shifts blame onto Semyon with a line that has since become famous, "It's not my fault, he came himself!" The next morning, Semyon wakes up in his apartment to find his wife and kids gone, with a note telling him that, now that she knows what his "special mission" is all about, she is moving back in with her mother and taking their kids with her. Fortunately, by the end of the film, the cops explain the truth to her, and she comes back.
In the film Easy Living, everyone thinks Mary Smith is J. B. Ball's mistress, because he gave her a sable coat and bought her a hat to match it.
In Enchanted, Giselle, just coming out of the shower, trips and falls on top of Robert, who had tried to catch her. Naturally, this is when Robert's girlfriend Nancy walks in and gets the wrong impresion.
In Finding Neverland, James's wife and several others believe that James and Sylvia are having an affair when he spends more hours with her and her sons than at home. In reality, he only saw her as a platonic friend. The wife eventually realizes the truth, but they still wind up divorcing, as she feels (perhaps correctly) that he cares about said friendship more than he does about their relationship.
In The Fly (1986), just as Seth and Veronica are celebrating his perfecting the telepods she discovers a package left at his loft by her editor — and jealous ex-lover — Stathis, which reveals that he intends to have his magazine jump her on the story of Seth's invention (which she is writing a book about). She leaves to confront him, and not wanting to get Seth involved in her personal drama just says it has to do with "residue" she has to "scrape off [her] shoe". However, Seth realizes that "'residue' means old boyfriend" and assumes she is cheating on him. He ends up getting drunk and decides to go ahead with the final step of the telepod project: teleporting himself, unaware as the timer ticks down that a fly is in the pod with him. A few hours later Veronica returns and she and Seth quickly reconcile as she explains everything — but the audience knows their happiness is already doomed, as strange hairs are sprouting from a wound on his back...
In Force of Nature: The Dry 2, Jill Bailey assumes her husband Daniel is having an affair with Alice Russell because of all the time he is spending with her. Daniel is actually working with her to find The Mole inside his company; not realising that Alice is the mole.
In The F-Word, Chantry surprises her boyfriend, Ben, by taking him up on his open ticket to Dublin where he's doing work for the United Nations. When he shows up, he's drunk and stumbling arm-and-arm with an attractive Brazilian co-worker. He maintains that it's entirely innocent, that they just drank a bit too much and were both headed back to their respective rooms in the shared housing. Nothing in the film contradicts his narrative.
Gone with the Wind:
- Scarlett pines over Ashley Wilkes, who married his cousin Melanie but courted her before then. Scarlett frequently urges him in private to run off with her, and Ashley is tempted but refuses. Then when Melanie is dying, she appears to tell Scarlett that it's alright to date Ashley after she's gone. Scarlett, however, is too upset to even think about that and falls crying into Ashley's arms... which several visitors spot and think Scarlett is Romancing the Widower.
- Earlier in the film, after agreeing to be friends despite the years-long UST, Scarlett and Ashley hug each other, only for Ashley's sister to walk in at that exact moment and get the wrong idea. The one person who believes in Scarlett's innocence is, ironically, Melanie.
In The Hand That Rocks the Cradle, the nanny gets the husband to plan a surprise party for his wife with their friend, who is the only one around the husband who smokes. When the wife finds her friend's lighter in her husband's suit jacket, she thinks he's having an affair, which she calls him out on with the next room full of party guests.
Hangmen Also Die!: Invoked. Mascha and Dr. Svoboda make it seem like they're having an affair to hide what they're really up to (Dr. Svoboda assassinated Reinhard Heydrich and Mascha helped him get away with it).
In The Holiday, Amanda "accidentally" checks Graham's phone with two incoming phone calls on the mornings Graham is with her and notices two girls' names ("Sophie, Olivia, Amanda. Busy guy"). Turns out Sophie and Olivia are his two young daughters' names.
Holy Spider: Fatemeh tells Saeed that a neighbour saw him bringing another woman to their house while she and the children were away and asks whether he has tired of her. In this case, the truth is far more sinister: he is a Serial Killer who solicits prostitutes before killing them.
Horrible Bosses: In Horrible Bosses 2, when Nick, Dale, and Kurt start arguing about whether or not Dale should have sex with Julia and risk jeopardizing his marriage so that she doesn't call the police on them, Dale's wife Stacy finds them, overhears everything, and runs off thinking that her husband is cheating on her.
Internal Affairs (1990): Invoked. Dirty Cop Dennis Peck knows the protagonist, Internal Affairs officer Raymond Avila, is following him, so he arranges to meet Avila's wife in a cafe where he discusses some innocuous business. He then assaults Avila in an elevator, taunting him about having sex with his wife and throwing a pair of panties in his face (which don't even belong to her).
I Saw What You Did: Because of the persona Libby adopts when phones Steve, she assumes that Libby and Steve are having an affair. She attempts to drive Libby off as a potential rival.
Played for Drama in It's a Wonderful Life, where one of the many, many things that cause George Bailey to hit Rock Bottom is his co-workers starting rumors about him and his friend Violet Byck after they witness him lending a large amount of money to her pro bono. In reality, of course, he did it because he's just that danged nice.
Jack Strong comes home late, if at all, generally neglects his family, so his wife starts suspecting an affair.
In Knocked Up, Pete is making up lies about work and sneaking out of the house so that he can go see his fantasy baseball league.
In Lethal Weapon 4, Riggs gets suspicious about Murtagh because his large expenses like on house remodeling seem impractical on a cop's salary. He eventually confronts Murtagh about it — in the middle of a firefight — where Murtagh is initially evasive about where the money's coming from before he eventually relents and asks if Riggs knows Ebony Clark, who writes what Riggs calls "cheesy sex novels".
Riggs: Wait, are you boinking her?
Murtagh: What, no! Trish^noteMrs. Murtagh is Ebony Clark!
Riggs: Oh! [thinks for a moment] You are boinking her!
Murtagh: ...Yeah, I guess I am!
The TV film A Love To Remember (2021) sees Tenley accidentally claim to be the wife of her online crush Jared when he has an accident and is left in a coma on the morning they were meant to meet in person. At one point, Jared’s girlfriend Larissa comes to apologise to Tenley as Larissa assumes she was basically Jared’s mistress (prior to this the rest of Jared’s family thought Larissa was just a good friend Jared dated years ago), but Tenley explains the truth and apologises for the misunderstanding.
Mabel's Blunder (1914) involves Mabel getting jealous after seeing her fiancé hugging an attractive woman. The woman turns out to be his sister.
Merry In-Laws: Peter's romantic rival Edward takes some pictures of Peter and an elf that makes it look like he's cheating.
Subverted in the Brazilian movie Meu Tio Matou um Cara ('My Uncle Killed a Guy') Éder finds a series of pictures that seem to indicate that his girlfriend Soraya cheated on him with Kid. She then explains to him that he looked at the pictures in the wrong order, and they tell the story of a perfectly innocent afternoon. Later, the protagonist Duca mentions to a friend that the sun's position in the sky doesn't match Soraya's story, and Eder was right after all.
Near the end of My Cousin Rachel (2017),Philip becomes suspicious of Rachel again and thinks he's having an affair with Rainaldi. Rainaldi is gay, and Rachel's actions and motivations remain unknowable as she dies shortly after.
In Mystic Pizza, Daisy (a poor Portuguese Catholic girl) sees her love interest Charles (a wealthy WASP guy) talking to a very attractive woman at a party. Consumed with jealousy, she persuades a lobsterman to dump his entire day's catch into Charles's expensive convertible sports car. Daisy then discovers that the woman Charles was talking to was in fact his cousin, leading to a memorable exchange:
Daisy: I fucked up.
Charles: Yeah... but you gave it a 100% effort!
Humorously inverted in Naked Gun 33⅓: The Final Insult. Lt. Frank Drebin first tells his wife Jane he's seeing another woman as a cover story, then Jane realizes that he's actually returned to his work as a detective despite agreeing not to.
Frank: I swear, it's another woman!
Jane: Oh, I wish I could believe that!
In Never Weaken, Harold Lloyd sees his girlfriend hugging another man who says "I'll marry you right away!" This sends Harold into suicidal despair. Unbeknownst to him, the other man is her brother, a minister, who is saying that he'll officiate her wedding to Harold.
Nothing to Lose is kicked off when the protagonist thinks his wife is having an affair with his boss and decides to rob the company in revenge. The evidence is seemingly incontrovertible (the boss' cufflinks are on the table, and they are going at it in the bedroom), but if he'd actually tried confronting them, he'd have found out they were relatives he wasn't told were visiting (and had a sudden case of the randiness). And the cufflinks had been there for months ever since the guy lost them during a party.
Oh. What. Fun.: While Taylor's current girlfriend DJ Sweatpants is out, Doug catches her sneaking a woman into the house. He later accuses her of cheating on DJ Sweatpants. It turns out that the woman was a straight jewelry maker — Taylor was planning to propose and had asked her to make a ring for DJ Sweatpants. This admission is not enough to save the relationship, as DJ was uncomfortable with Taylor's long dating history.
Pirates of the Caribbean: Dead Man's Chest: At the end, Elizabeth passionately kisses Jack, not knowing that her fiancé Will is watching. She was actually distracting Jack so she could handcuff him to the ship.
Planes, Trains and Automobiles: Originally, there was an entire subplot where Neal's wife suspects that he's having an affair and that "Del" is merely a persona he's created to explain why he hasn't arrived home yet. The tears of joy when Neal finally comes home and introduces Del to everyone was originally supposed to be elation upon discovering that Neal was telling the truth the whole time.
Shall We Dance (2004): A woman becomes suspicious of her husband when she realizes that he's displayed the same traits that a friend's cheating husband is — late nights, distraction, etc. As it turns out, while the husband is bored with his life and having a mid-life crisis, he isn't cheating on her, he's taking dance lessons. However, the wife is still concerned about the possibility of him having an affair with one of the dance instructors.
Shallow Hal: Played with. Hal does accept an invitation to dinner with former flame Jill (with her romantic intentions fully visible) while he and Rosemary are estranged, but still together. But when Jill turns up the gas and propositions Hal, he (after some consideration) refuses, finally realizing that he really wants to be with his "Rosie", regardless of her looks. But this realization comes to late, as Rosemary sees the two holding hands...
The Shop Around the Corner: Inverted. Mr. Matuschek knows his wife is cheating with one of his employees and comes to the conclusion that it is Mr. Kralik. It's really Mr. Vadas.
Short Cuts zigzags the trope with extramarital lovers Gene Shepard and Betty Weathers. Betty has another boyfriend, Wally, with whom she is planning to spend the weekend, and has roused Gene's suspicions with a flimsy cover story. He tries to call her, but her soon-to-be ex-husband Stormy answers the phone instead and engages in a bit of Relationship Sabotage by shouting at Betty to put her panties on. That evening, Gene shows up at the house to see Stormy's car parked in the driveway and Stormy himself in silhouette through the bedroom curtains (unbeknownst to Gene, Stormy is instead destroying the contents of the house as an act of revenge against Betty while she is away with Wally). The enraged Gene throws a rock through the bedroom window and goes back to his wife.
In Smiles of a Summer Night, Count Malcom barges in on Fredrik wearing the Count's nightshirt and robe at Desirée's place. Fredrik had earlier fallen into a large puddle of water and changed into the only dry clothes available.
In the film Stars And Stripes Forever two members of Sousa's band (female singer and male Sousaphonist) are secretly married. When the Spanish-American War breaks out he reenlists, and they spend his last night before shipping out holding each other in an Italian restaurant. The restaurateur suggests that they should get married so they'll have a place to be together. "Oh, we are married. That's why nobody can see us." After they leave, the restaurateur tells his wife that the couple should divorce their respective spouses and marry each other since they obviously love each other so much.
Taxi 2:
- The film starts with protagonist Daniel (Samy Naceri) driving a woman in labor to the hospital in his souped-up taxi. Despite driving the fastest he can, they arrive too late and the woman has to give birth on the backseat of his taxi. Just at this moment, Daniel's girlfriend Lilly (Marion Cotillard) calls him on his cellphone and hears the woman's screams, which sound like immodest orgasms. Then Daniel has to explain the situation to her and she has some trouble believing him.
- Later, when Daniel's taxi is used for an operation to rescue a Japanese minister from a gang of Yakuza that have kidnapped him, Daniel's taxi is literally parachuted over Paris. When descending, Lilly calls again just as the female Japanese agent tasked with finding the minister is massaging Daniel's Nervous Wreck cop friend Émilien and singing to him, leading to Lilly thinking they're in a Thai salon (implying sex things). Daniel has to clarify once again what they're actually doing, and Lilly is even more perplexed due to the absurdity of the situation.
That Lady in Ermine had this, due to Executive Meddling. Angelina's husband thinks she slept with the Colonel to make him leave (it was the ghost of her ancestor in a dream, convincing him to leave).
An odd example in Top Hat. Dale has confused Jerry for her friend's husband, Horace. Jerry loves Dale and Dale is convinced he's trying to have an affair with her.
Trading Places: Clarence Beeks pays a hooker, Ophelia, to act like she's involved with Louis Winthorpe while he's reconciling with his fiancée Penelope, to further sabotage his life (she only agreed due to the generous payment). However, Ophelia soon takes pity on Louis, so she takes him in and later falls in love with him for real.
In Transformers: Revenge of The Fallen, Mikaela walks in on Sam apparently sharing a passionate moment with an attractive co-ed, and storms off in a huff as Sam desperately protests that it's Not What It Looks Like. Said co-ed is actually a sexually aggressive Decepticon Pretender trying to get at the data embedded in Sam's head; the instant Mikaela leaves, the Pretender gives up on the Fake-Out Make-Out and starts attacking Sam properly.
In When the Bough Breaks, thanks to Anna's manipulations, Laura is led to believe John had been having an affair with her. But she soon realizes the truth.
On White Chicks, Marcus' wife Gina thinks he is cheating on her while he and Kevin were undercover as famous female white twins Brittany and Tiffany Wilson and staying at a hotel hanging out with the girls' friends. She overhears one of the twins' friends on the phone and catches him at the hotel room with "Tiffany" (actually Kevin in disguise).
Occurs in Who Framed Roger Rabbit, when Jessica Rabbit visits Eddie Valiant to ask for his help with her case. On the line "I'm desperate Mr. Valiant, can't you see how much I need you," Valiant's girlfriend walks in. It doesn't help that his pants are down as well.
When Lucy announces that she's pregnant in Written on the Wind, Kyle assumes that Mitch is the father due to his own fertility problems.
Yes or No: When Kim is sick in bed with a migraine, she wears a blindfold while she recovers. Jane seizes the opportunity for a sneaky cuddle and Kim, thinking her to be Pie, reciprocates. Then Pie walks in. Per usual romantic drama cliché, Pie reacts in anger and storms out before getting an explanation from Kim, so it takes some time for her to clear this up.

Jokes

A man is taking some time to get home, so his wife calls her mother. "He's cheating on me, I just know it!" "Now, dear, why do you always assume the worst? Maybe he had an accident!"
Inverted with one where a man tells his wife he's going out for cigarettes. He finds the store closed, so he goes to the bar to use the machine, and when there decides to have a few drinks. He gets a little drunk, begins talking to a woman at the bar, and before you know it they're in bed together. He wakes up and realizes he's in trouble, and quickly asks the woman for some talcum powder which he slaps onto his hands. When he gets home, his wife is waiting up and demands to know where he's been:
Husband: Well, I went to the bar because the store was closed, had a few drinks, met a woman, went home with her, and had sex with her.
Wife: Let me see your hands! (Sees the talcum powder) Liar! You were out bowling again, weren't you?!
And defied with the tale of the man who got so plastered-assed drunk he ended up passing out on the front lawn and defecating his pants. He wakes up the next morning to find himself spic and span and in bed, and heads downstairs to find his wife in a cheerful mood cooking him a fabulous breakfast. Struggling to remember the night before he asks what happened and she explains that she dragged him inside so the neighbors wouldn't see and, upon realizing he had messed himself, attempted to clean him up. When she tried to remove his pants he sloppily shoved her away and yelled "Piss off, ya slag! I'm married!"
"My wife found out I was cheating when she found the letters I was hiding when cleaning up our place the other day. She said she's never going to play Scrabble with me again."

[[folder:Literature]]

Turns up regularly in the works of P. G. Wodehouse, often on the most hair-triggered and flimsy of pretexts.
The Alice McKinley Books has Alice think her stepmother, Sylvia, is cheating on her father a few times. When she learns that Sylvia's ex is going to Chester, where Sylvia is currently working as an exchange teacher, for Christmas, Alice thinks she's cheating and will continue to see him, even after getting married to Ben. Sylvia tells Alice that she had no idea that her ex was going to do this and sent him packing. Another time, Alice saw Sylvia getting out of her ex's car and tried to avoid thinking this. Sylvia says that she was playing tennis with some friends and her ex was substituting for someone.
In Honore D'Urfe's L’Astrée the shepherd Céladon is shown to his love Astrée while he is reciting poetry to another by a jealous suitor looking to break them up. Despite the fact that Astrée herself had told Céladon to pretend to romance another to hide their relationship because their parents disapproved she thinks he was cheating on her and banishes him from her sight, leading him to try and drown himself in the river.
In A Brother's Price, Jerin manages to mistake himself for cheating - when he can't remember a certain period of time, he fears that he cheated on his fianceés in that time, as he was there with a woman, and can't recall what, exactly, happened, only that it was a compromising situation. Turns out the mysterious strange woman is, in fact, one of his wives-to-be, and she cheerfully tells him that, if he thinks that was sex, she will have to give him The Talk.
Happens in The Century Trilogy when a character returns home from the war to find his girlfriend has had a baby and he's not the father. He starts to storm out, and she hastily explains that she was raped by several soldiers from the occupying army.
Chalion: A retroactive variant comes up in the backstory of Paladin of Souls. The cover story of espionage and bribery used to explain Chancellor Arvol dy Lutez's death in the dungeons of the royal castle some 16 years back was fairly transparent if one thought it through, so many (including the Chancellor's son) concluded that he had seduced the King's young wife and been caught out.
The 16th Century Vietnamese Collection of Strange Tales has a story where a man, after coming home from the war, got rejected by his three-year-old son who claimed that 'his real father' always 'appears every night, stands when mother stands, sits when mother sits'. The husband thought his wife was unfaithful to him and kicked her out of the house without waiting for an explanation. The wife, in despair, drowned herself in a river. It wasn't until night came and the son pointed at his father's shadow on the wall, exclaiming 'That's my father!' that the husband realized that his deceased wife, who was just trying to calm their son (as he missed his father who was away at the war) with a white lie, had been innocent after all.
In The Color Purple, until the day she died Corrine thought that her husband was cheating with his friend Nettie. This is because Corrine's adopted children have a Strong Family Resemblance to Nettie. As it turns out, her kids are the biological children of Nettie's sister Celie. Corrine refused to believe Nettie and thought she was lying about being their aunt.
In one of the Confessions of Georgia Nicolson books, Georgia believes her mother is having an affair with the builder (apparently not true, her mother just liked to flirt with him.) Leads to a humorous incident where Georgia skips school to spy on them, but they open the door and she falls through it, forcing her to pretend she had been sent home sick.
Subverted in Reginald Hill's Dalziel and Pascoe novel Death's Jest Book, in which Sgt. Wield gets into a paternal relationship with a rent boy that sure makes it look like he's cheating on his partner—even Dalziel thinks so—except that he isn't. Ironically, Wield's partner is the one who hangs a lampshade on the situation by pointing out that he has complete faith in Wield's motives.
Dancing Aztecs:
- Chuck Harwood keeps believing his wife Bobbi is sleeping with their friends and patronizingly saying he doesn't care but is annoyed she lies about it. Bobbi in fact isn't sleeping with any of them but gets so fed up with this that near the beginning of the book she leaves Chuck and throws his clothes out the window.
- F. Xavier White's wife is convinced he's in love with his assistant, although there's nothing in the text to support this.
- When Kenny and David catch Jerry in their apartment, trying to steal their statutes, each of them believes that he's a guy the other one picked up for casual sex, and tries to pretend it's no big deal even as their clearly hurt by the implications.
The Faerie Queene: Belphoebe sees Timias embracing Amoret and assumes he's being faithless to her, not realizing Timias is attending to Amoret's wounds. She leaves before he can explain and he becomes a hermit in despair.
In Flawed, after escaping Logan's shed and being tormented all night, Celestine runs into her boyfriend Art and her sister Juniper. As this came after she had a fight with Art, her immediate reaction was to assume they were both going out behind her back. Juniper, however, later insisted that they were just friends who bonded over how worried they were for her.
Help I Am Being Held Prisoner: One of the hostages during the bank robbery calls her husband to make an excuse for why she won't be home and he accuses her of having an affair, causing her to angrily say he can call back and she'll still be there.
In Harry Potter and the Order of the Phoenix Cho gets this impression of Harry on their date, thanks to his poor choice of words in describing his meeting with Hermione later.
In House of Mirth, Lily Bart is unfortunately — and wrongly — cast in the role of the "other woman". Once by a so-called friend who is trying to cover up her infidelity, another time by a man whose advances she has rebuffed.
Hurog: In Dragon Bones, Erdrick thinks his brother Beckram is getting himself in danger by having a secret affair with the (married) Queen Tehedra. Turns out, no, Beckram was asked to share her bed by no one else than the king. (Who seems to prefer young men, anyway.) So, yes, he is sleeping with her, but it is not cheating.
The Innkeeper Chronicles: In Sweep of the Heart, Officer Marais' wife Donna has grown suspicious of his late hours "at work" and has found out at his precinct that he's actually taken vacation from his normal job. She tracks him to Gertrude Hunt, where he's moonlighting as security for a large event, and accuses him of having an affair with the first woman she sees, which is Dina. Dina defuses the situation by inviting her in to discuss things a little more privately, and essentially walks her through a Bar Full of Aliens to give her context for the upcoming explainations.
Jaine Austen Mysteries:
- Jaine's father thinks her mother is cheating on him with a Home Shopping Network salesman in Last Writes. She's not.
- He later suspects his "arch rival" Lydia Pinkus is having an affair with a married man in Murder Gets a Makeover, after hearing what he thinks is her voice calling into a radio psychiatrist's show, seeing what he believes is her meeting with a man in a fancy restaurant, and overhearing Lydia book a motel room while tailing her. She isn't, and the motel room was to accommodate her cousins flying into Florida.^note
In Jinx High by Mercedes Lackey, Deke decides that the reason his father and Diana Tregarde are spending time alone together is that they're carrying on an affair. The real reason is to track down the mystical danger that wants Deke for lunch. To be fair, Deke wasn't aware of his own mystical abilities until late in the novel, and certainly wasn't aware that his parents had been part of Diana's Scooby Squad in their college days.
In "Julius Katz and a Tangled Web," the married murder victim and a coworker who has a boyfriend were seen sneaking off to a motel together. They weren't having sex, though, but instead needed a private place to conduct a secret audit to catch an embezzler.
In a Nancy Drew/The Hardy Boys Supermystery novel, Frank was half-carrying Nancy across a parking lot (she'd sprained her ankle), when they encountered her boyfriend Ned Nickerson. Already ticked off, he was even more so when she declined his offer of a date that evening, as she and Frank had to work on their case, thus confirming his incorrect suspicions that something was going on between them. The subversion here is that Frank and Nancy were quite attracted to each other throughout this Crossover series, so Ned's discomfort with their friendship wasn't entirely unjustified.
My Next Life as a Villainess: All Routes Lead to Doom!:
- Maria's ability to use magic led to rumors that her mother had an affair with a nobleman due to how insanely rare magic is among commoners. The truth of the matter is that no cheating had taken place, but her father eventually came to believe the rumors and walked out on the family.
- When his daughter Catarina becomes engaged to the third prince of Sorcier's royal family, Duke Luigi Claes is left without an heir. He adopts the son of a distant relative, Keith, to become the new heir. However, miscommunication and her own insecurities lead his wife to think that Keith is Luigi's illegitimate child (Keith is an illegitimate child, but between the distant relative and a prostitute). In the Fortune Lover storyline, this results in her treating the boy coldly. In-story, Catarina's antics lead to the issue being cleared up and Luigi being vindicated.
Used tragically in Needful Things. Fiancées Lester Platt and Sally Ratcliffe are led to believe that each is cheating on the other. Lester beats her unwitting suspected lover half to death before being killed by the police, and after finding out about this, Sally hangs herself in her closet.
Happens with Denise and Spade in the Night Huntress books when she's told that "the vampire" is in a bedroom with another woman. She furiously pounds on the door only to find she's got the wrong vampire.
One Fat Summer: Over the book, Marty Marks keeps leaving his family's vacation house on Rumson Lake to return to New York City, while his time on the lake is spent arguing with his wife. His son Bobby suspect Mr. Marks of carrying on an affair, a suspicion he shares with his sister Michelle, only for her to tell him he's an idiot. It turns out Marty is actually going back because, after some bad investments, Marty has wiped out his family's savings and is now desperate to find a way to keep them solvent.
The Parasol Protectorate: This becomes a major plot point when the wife of a werewolf (which are infertile in this setting) turns out to be pregnant. The wife in question is Alexia Maccon, a walking Power Nullifier who turns her husband mortal while in physical contact with him. Which she had to be during conception.
In the Paradoxes of Mr Pond story "The Crime of Captain Gahagan" by G. K. Chesterton, when Frederick Feversham is murdered, the obvious suspect is Captain Gahagan, who everyone assumes was having an affair with his wife, as evidenced by the fact they spent a lot of time together, quite late into the night. The paradox Pond realises is that they spent too much time together to be having an affair. Gagahan's actual love affair is conducted in dramatic whirlwind meetings; what he had with Mrs Feversham was simply friendship.
The Quorum: The best and longest-lasting romantic relationship in Neil's life comes to an abrupt end after he steps into a pub for a quick drink with an old friend, only for a series of unfortunate accidents to result in him faceplanting into a compromising position with a young lady just as his girlfriend comes in to see where he's got to. She refuses to believe that it's just an accident, and in a way she's right: the whole thing was carefully orchestrated by the old friend, for an ulterior motive Neil doesn't find out about until much later.
Red Dwarf: Better Than Life: Lister, who has been enjoying a happy fantasy life with a wife and two kids, is suddenly shunned in disgust by his entire community when a very obvious prostitute shows up looking for him, despite his insistence that he's never met her in his life. It's actually Rimmer in said prostitute's body.
Septimus Heap: When Sally Mullin sees Silas and Marcia fleeing from the Custodians she thinks they are eloping. Sally also thinks Jenna was conceived by Sarah in an affair because Jenna doesn't look like Silas or Sarah (Jenna is actually secretly adopted).
Southern Fried Rat and Other Gruesome Tales: An anthology collecting a number of stories based on varied urban legends, including The Solid Cement Cadillac, in which a perpetually suspicious husband, who drives a cement mixer and comes home to check on his wife one day, finds a brand new Cadillac in the driveway. Sneaking up to the house, he sees her in the kitchen, talking with another man. Assuming she's cheating on him and that the unfamiliar car is the man's, he fills the Cadillac with cement and drives off. When he returns home that evening, he finds his wife in tears and learns she had bought him a Cadillac as a surprise, only to have someone fill it with cement while she was signing the delivery papers.
Star Wars Legends: In the novelization of Revenge of the Sith, Palpatine (who is fully aware of Padmé's and Anakin's secret marriage) insinuates that Padmé is cheating on Anakin with Obi-Wan. When Anakin visits Padmé's residence to confirm these suspicions, he detects signs that Obi-Wan did visit her (to share his concerns about Anakin). While Padmé is able to assuage his temper, Anakin never really lets go of the insidious notion. Later on Mustafar, when Anakin sees that Obi-Wan stowed away on Padmé's ship, he takes it as a sign that Padmé has betrayed him. Cue Force-choking.
In one of the Stephanie Plum books, Steph thinks Morelli's reviving an old affair with Terry Gilman. Turns out it's a business matter, and she nearly screws up a case the FBI has been working on for months when she confronts him.
In a Sweet Valley High book, the twins and their older brother Steven become concerned about their father's apparently budding relationship with a coworker. It's never established if they were completely wrong or if there was something brewing before the father had the sense to end it before it could really get started. Earlier, in a Sweet Valley Twins book, the kids become convinced that their mother is having an affair with one of her clients and is planning to run off with him, even though there have actually been zero signs to that effect—they've simply taken everything nice that their mother says or does as romantic interest and when they take to spying on the man, they mistake his phone conversations with his girlfriend for lovey-dovey chats with their mother.
Happened many times in the Teenage Worrier series:
- The Teenage Worrier's Guide to Life: Letty's mother disappears, but the family finds a note from "Neville" (the name of her ex-boyfriend) agreeing to pick her up. It turns out Neville is the husband of someone she was visiting to discuss a business venture, but she'd accidentally left his note to her on the table, rather than the note she had written for her family.
- In The Teenage Worrier's Worry Files, Letty meets a man named David who is a cross-dresser. She discovers letters between David and her father, describing plans to go on a trip together; and believes they are having an affair. David was actually helping him research for a new novel about a cross-dresser.
- In another book, Letty visits her friend Hazel's house to send her ex-boyfriend an email (since Letty doesn't have internet access at home.) His new girlfriend intercepts the message and writes a reply warning Letty to stay away from him, but Hazel's mother finds it and assumes her husband is having an affair. Hazel isn't happy with Letty.
- In The Teenage Worrier's Christmas Survival Guide, Letty asks to borrow a dress of her mother's to wear to a Christmas party, but the dress turns out not to belong to her mother, leading to an argument between her parents over whose it is (though it is suggested her dad isn't really cheating).
Tortall Universe: In Trickster's Queen, Aly creates and plants fake evidence suggesting that Prince Regent Rubinyan is cheating on his wife Imajane with one of her ladies-in-waiting to drive a wedge between them for the rebellion's benefit. It results in both Imajane throwing a chair at her husband, and the lady in question being sent home covered in bruises.
In the Warrior Cats book Hawkwing's Journey, after Plumwillow and Hawkwing's mates go missing, Plumwillow asks for Hawkwing's help in raising her kits; both of them always intend it to be platonic. Eventually her mate Sandynose finds his way back to the Clan, and when Plumwillow introduces him to the kits, they're confused and say that they thought Hawkwing was their father. Sandynose narrows his eyes at Hawkwing and is about to speak when Plumwillow explains that they're Just Friends and that she just needed help and that the two had been through the same thing when they lost their mates. Hawkwing confirms this, wanting to make it clear to Sandynose that he hasn't stolen his mate.
Whateley Universe: As can be expected in a series which combines Teen Drama and superpowers, this has come up a few times:
- Phase (Ayla Goodkind, formerly Trevor) has been dating Vox (Vanessa Jackson) since their first day at Superhero School Whateley Academy, and are happy together for most of their freshman year. However, Vanessa has always been uncomfortable with the power dynamic in the relationship (since Ayla is immensely wealthy, and she doesn't want to be seen as Gold Digger), and very sensitive about to possibility of him cheating, since her father had left her mother for another woman when she was young. She grows suspicious of his friendship with She-Beast (Jadis Diabolik), despite knowing that they had been Childhood Friends and had no interest in each other romantically. She eventually can't take it any longer, and after she sees Jadis give Ayla a friendly kiss on the cheek, goes into a full-blown jealous rage.
- After Lucas Del Bosque's girlfriend, Jamie Howe, manifests as a Devisor, he is the only one who stays by her side, even when she begins show clear signs of severe Diedrick's Syndrome. Unfortunately, Luke is a Clueless Chick-Magnet, having eyes only for Jamie despite nearly every other girl in school wanting to get with him, and some hatch a plan to break them up by convincing the insanely jealous (and just plain crazy) Jamie that he is cheating. It works far too well for anyone's good, and Jamie, now in full-blown Yandere Mad Scientist mode, zaps Luke with a Transformation Ray that permanently turns him into a near-exact copy of superheroine Iron Bunny. He is sent to Whateley as soon as feasible, only to find that Jamie was also sent there as part of her probation. Jamie (who is given the Code Name Calibrate), now fully psychotic, is convinced that Lucretia (the former Luke, codenamed Lapin) is the girl who stole Luke from her, and harasses the 'slut-bunny' to make her give him back.
In You Don't Own Me, Kendra is convinced her murdered husband Martin was having an affair and that she would "bet [her] life" on Leigh Ann Longfellow being the other woman, as they were constantly spending time together, much more so than the time Martin spent with his wife and kids. Martin, the Longfellows and Martin's parents all adamantly denied there was an affair and the police found no evidence of one either, with Leigh Ann explaining she and Martin were childhood friends who both began working together on their school's alumni board and that's why they were so frequently in contact. It's then subverted when it's confirmed they were having an affair, with Leigh Ann and Daniel having separately gone to great lengths to conceal this and Martin trying to gaslight Kendra into thinking she was just being paranoid.

Music

ABBA song "Crazy World" has the narrator spot a man entering his girlfriend's house. Turns out it's just her brother, who she apparently never told him about before.
The Mecano song "Hijo de la Luna", covered by Sarah Brightman. A Romani woman makes a deal with the moon to find her a husband, as long as she agrees to give up her first-born child in return. The baby ends up as pale as the moon, instead of resembling its dark-skinned father. Her husband ends up killing her, and the moon gets its child.
Played darkly in mothy's Vocaloid song in the Evillious Chronicles, "The Tailor Shop on Ebizaka" where the tailor was upset that her lover hasn't been coming home to her and finds out he was seeing three different girls on different occasions. She kills the three girls and took their clothing/accessories thinking it would make her beautiful to her lover. It turns out that her "lover" doesn't even know who she is and the three girls were his wife and two daughters. She then kills him too, offended by his lack of recognition.
"Happy" by Mitski covers this. It features a protagonist watching her happy marriage fall apart after her husband returns home from war. She becomes increasingly suspicious of the jewellery he gives her, and where he goes late at night. Despite having dark hair and eyes, she finds a lock of blonde hair and 'For My Blue-Eyed Cookie' embroidered on a bag he gave her. It is all but confirmed that he is having an affair, as we see various shots of him seducing different women. And then she goes down to the basement... To find him hacking a female corpse with an axe and removing her jewellery to clean. The shots of him seducing women now show him smothering them with chloroform. Unfortunately, he spots the wife as she trips trying to run away and starts to choke her. Fortunately, she manages to grab the axe and (presumably) kill him. We then see shots of her driving away.
Implied in the Christmas song "I Saw Mommy Kissing Santa Claus." Because "Santa" is presumably the child's father wearing a costume.

Myths & Religion

In the Biblical account of the Nativity of Jesus, Joseph initially assumed that Mary's virgin pregnancy was the result of infidelity, until an angel explained the truth to him.
One Jewish legend says that David was conceived due to a Bed Trick after his father, Jesse, stopped sleeping with his wife; as a result, Jesse assumed David was the product of an affair throughout his childhood.
In the Ramayana, Sita is held hostage for a year in Ravana's palace, during which time she turns down all of his advances, because she is Happily Married to Rama. When she finally gets out, Rama assumes that she slept with Ravana and wants no more to do with her. Sita agrees to undergo a Fidelity Test involving walking over flames, and passes the test with flying colors. In some versions, this appeases Rama, but in others, it's still not enough to convince him.
In Hawaiian mythology, Pele saw her sister embracing one of Pele's lovers. The pair had bonded over the course of a journey they undertook on Pele's behalf, and the embrace was platonic. However, Pele assumed they were having an affair, and drowned them in lava, which killed her lover. In a dose of pure irony, once Pele's lover was resurrected by Pele's sister, he actually did chose to be with the sister rather than Pele and the two became lovers for real.

Radio

Happens twice in The Space Gypsy Adventures (oddly enough, both episodes were written by Space Gypsy guest contributor David Monid):
- The first time, in Damien's Valentine's Day Panic, is covered in Relative Error, but in short, Jehlise accuses Damien of dumping her in favour of 'one of his own kind'(the other girl is a fox cub with raccoon markings, like Damien). Luckily for her (and arguably for Damien as well), it turns out that it was actually a supposed cousin of Damien.
- It next happens in The St. Valentine's Day Mix-Up. When Gemma discovers that a Valentine's card from Duke has Fluff Catt's name inside it, she goes absolutely berserk at him and throws him into the Spaceport duck pond. She finds out later that the card for Fluff was actually from DC Bones, who had asked Rekki to pass it on to Fluff but had forgotten to sign it with his own name.

Tabletop Games

Some of the villains of Ravenloft have this trope in their backstory. Anton Misroi caught his wife in the arms of another man, whose shoulder she'd been crying on because Anton was so cruel. Romir Hiregaard leapt to conclusions after seeing his wife and a family friend arm in arm, unwilling to believe that he'd interrupted a waltz lesson. In each case, the wives wound up murdered, and the villains, cursed by the Dark Powers.
The backstory for the Painted Bride begins with a nameless bride visiting her parents' graves so that they could see her in her bridal gown, with her husband-to-be following her because he assumed that she was sleeping with another man. The bride fled, but her fiancé hunted her down, stabbed her to death, and buried her in a little-used corner of the graveyard.

Theatre

William Shakespeare used this plot device:
- It's played extremely seriously in Othello, when the title character believes that he overhears his friend Cassio laughing about sleeping with Othello's wife. Cassio is in fact talking about another woman entirely, and the whole thing had been set up by the villain of the piece in order to mess with Othello's head, but nobody discovers this in time to prevent the usual Shakespearean tragedy ensuing.
- In The Winter's Tale, the plot is driven by King Leontes suspecting his wife, Hermione, of cheating on him with his best friend, King Polixenes.
- Played for Laughs in The Comedy of Errors. Adriana rationalizes all the absurd behaviorm of "her husband" under the assumption that he doesn't love her anymore and is covering up an affair. All of the absurdity she actually notices is a result of the Twin Switch, but unbeknownst to her and the audience, her husband is seeing a courtesan at the same time!
In The Cat and the Fiddle, Victor spends most of the second act under the mistaken impression, furthered by Odette, that she has been sleeping with Daudet.
The Children's Hour revolves around this. A little girl accuses her two female teachers of having an affair in order to avoid going to school. It ruins their social lives, ruins their teaching careers, and Karen's fiancé leaves her due to doubts. The 1933 film adaptation These Three changed it into accusations Joe was cheating with Martha, though the 1960 remake keeps the original plot.
Lord Windermere in Lady Windermere's Fan. The woman his wife suspects him of is actually blackmailing him with a secret he wishes to protect his wife from. She redeems herself later on, though.
This happens to Fiyero and Elphaba in act 2 of Wicked. Somewhat subverted in that Fiyero most definitely did want to be cheating on Glinda at the time.

Urban Legends

An urban legend which dates back to at least the 1970s involves a man finding a strange car in his driveway, assuming it belongs to his wife's lover, and pouring cement into it — only to realize too late that the car was a gift from his wife and that what he assumed was her lover was actually the car salesman. In other variations, the wife is cheating, but the lover leaves the house with a different vehicle from the freshly-cemented one. Don Tyson, late CEO of Tyson Foods Inc., was involved in a version of the tale where his wife spotted his car in another woman's driveway and called a cement company to dump cement in his car, which was dismissed as apocryphal by the company.
One urban legend tells of a woman whose husband goes to a costume party without her. As a Secret Test of Character to make sure he's faithful, she buys a costume and attends the party pretending to be somebody else. After successfully seducing a man who was wearing her husband's costume, she returns home, planning to reveal that she caught him intending to sleep with a woman who wasn't her... only for him to come back with a bundle of money. As he explains, he spent the party playing poker with some friends; he loaned his costume to a guest who showed up without one, saying the guy apparently had a great time.

Video Games

Amnesia: Later pulls this in Ukyo's After Story. The heroine finds notes that make it appear like Ukyo is living with another person, assuming it's a woman, and she worries that this is why Ukyo was so against the two of them spending time together in the evening or was hesitant to invite her over to his place. When Ukyo learns of her worry, he explains that he has a split personality, the notes are a way for the two of them to communicate, and that his split personality is more likely to appear when Ukyo is tired, hence keeping himself away from her when it gets to nighttime.
In Batman: The Telltale Series, this possibly happens in the third episode. The player, as Batman, can choose to sleep with Catwoman, whose civilian alter ego is currently in a relationship with his (Batman's) best friend Harvey Dent, or choose not to. Regardless of the choice, the next day will have Harvey come over, see them in states of undress, and assume (correctly or not, depending on the choice) that they slept together.
In BioShock Infinite this befalls the Big Bad and Dark Messiah Father Comstock. Over-exposing himself to machinery that let him see the future have rendered him sterile, meaning he stole "his" daughter from an alternate-reality version of himself who never became Father Comstock. He told his wife it was a miracle child that God had made from whole-cloth, which she understandably finds hard to believe and accused Rosalind Lutece of sleeping with him. Rosalind responds by telling her what really happened, which she finds even harder to believe, eventually leading Comstock to murder her to keep her from spreading doubt.
Cyberpunk 2077 has a sidequest, "Raymond Chandler Night", where a bartender asks V to investigate his wife, whom he's sure is cheating - their son looks nothing like either of them and she can't account for her movements. If V looks into it, he finds her entering a strange building... the shop of an underground ripperdoc. Turns out she's heavily modded almost every aspect of her appearance, which she hasn't told her husband about out of shame, but those mods don't alter your genes any - her son takes after her actual looks.
Invoked and played for laughs at the beginning of Duel Savior Destiny. Taiga is currently attempting to get a hundred girlfriends at once and calls one of them by the wrong name, at which point he attempts to play it as a joke with this trope. She doesn't buy it.
In The Elder Scrolls V: Skyrim, Ranmir thinks that his fiancée Isabelle "ran off with a thief named Vex", assuming that Vex is male and that Isabelle was cheating on him. Turns out that Vex is actually a woman, Isabelle's old friend, and that she had gone to Vex to ask if she knew of any treasure; Isabelle wanted to fix Ranmir's financial problems and make him happy. She had died in the attempt. The player gets to show Ranmir a note she had written before her death explaining everything.
In Fantasy Life, part of the prologue for novice Miners involves helping out Master Duglas, who hugged a strange woman in a case of Mistaken Identity and, in the process, lost his anniversary gift for his wife Ruby.
Fate/Grand Order: When Altera and Brynhild meet for the first time, Brynhild sniffs her and smells her lover Sigurd's scent. She concludes Altera must have slept with him and angrily attacks her. Altera and Mash realize that Brynhild smelled Siegfried's scent on Altera and mistook it for Sigurd's, since the two men come from similar myths. And the reason why Altera has Siegfried's scent is that she had married Siegfried's wife Kriemhild. They try to explain this to Brynhild, but she won't listen, so they are forced to beat her into submission.
Fire Emblem: Awakening:
- Sorta. When Chrom shares a hug with his Kid from the Future Lucina before they explain their relationship, they get caught... by Lucina's mother, who has no idea of what's going on, and ends up wondering if they're having an affair (The exact reactions are different per girl). They explain the situation, Lucina hugs her still shell-shocked mother, and everything will be solved.
- If Chrom and a female Avatar DON'T get married, the Avatar's supports with Lucina will involve the latter accusing the first of either being Chrom's lover or intending to seduce him.
In Galaxy Angel Moonlit Lovers, Ranpha suspects Tact of cheating on her with Chitose because she walked in on their hands touching while picking up papers. He spends much of the rest of the story path trying to win her back, eventually dressing up in a ridiculous pink "I love Ranpha" outfit. Similarly, Mint in her route seems to assume the worst when a sleepy Chitose hugs Tact and mistakes him for her father, though her reason for getting upset is more that her telepathy isn't working, so she can't read Tact's mind to be sure he's telling he truth.
- In Eternal Lovers, on every route (except Forte's) Tact finds himself in several compromising situations with Lushati, leading the Angel to suspect he may be losing interest in her. As it turns out, Wein was intentionally causing this in order to drive a wedge between them, since the Valfasq had gotten wise that their bond together was the Angel Wing's main source of strength.
A Hat in Time: Queen Vanessa, already an unhinged Clingy Jealous Girl who seethed when her prince studied law abroad under a female professor and tried to ban bacon from the house because she was afraid he loved it more than her, had her paranoia vindicated when she caught him holding hands with another woman. The woman was actually a flower seller and the prince was merely handing her money because he was buying some flowers for Vanessa. Unfortunately, the sight had caused Vanessa to completely snap and chain her prince in the basement to make good and sure he would never leave her, where he remained until he transformed into The Snatcher.
Played for Drama in the fourth volume of June's Journey; June's relationship with her husband Jack has been strained for a while because of her working as a spy behind his back, but when Jack wants to talk to her and finds her kissing her spy partner Nathaniel with whom she's going Undercover as Lovers on the regular, he assumes the worst, especially since June doesn't stay to explain the situation to him but instead runs off yet again.
The Legend of Zelda: Majora's Mask: When Anju's fiancé Kafei disappears less than a week before the day of their wedding, her mother assumes he has run off with Cremia, Anju's best friend (who is revealed to have a crush on Kafei herself by her younger sister Romani). It's suggested that Anju's father ran off on her mother years ago, explaining why she's so quick to make such an assumption. Then, on the First Day, Anju receives a letter from Kafei where he states that he will return, leaving Anju scared that he might actually want to break things off with her and too afraid to write back to him without Link's prompting. As it turns out, Kafei was transformed into a child by the Skull Kid, and his ceremonial wedding mask was stolen shortly afterwards by the thief Sakon. He doesn't particularly feel like he needs to hide his transformation, but he absolutely refuses to return to Anju or even let her see him until he recovers the mask, as it is meant to be used as part of their wedding vows.
Love & Pies: Raj's wife, Gita, hires Yuka to follow Raj's movements because she thinks he is cheating on her. It's later revealed that Raj was acting strange because he was secretly building a two seater bike for him and Gita.
Love of Magic: Zig-zagged. Emily in the Alternate Timeline assumes that Owyn's sexual relationships with his Chosen mean he's been cheating on original-timeline Emily all along. However, Molly becoming a Chosen forced original-timeline Emily to realize that she was dating a literal Sex God, and her honor required her to accept this after Molly helped her save Owyn's life, so he was in fact not cheating. Alternate Timeline Emily doesn't understand this at first, and doesn't see how she would ever condone her husband having sex with other women, so she concludes that he is cheating, and doesn't trust him initially because of this.
My Café has a hilarious variation in which Bill believes himself to have cheated on his fiancée while getting drunk during his stag party: he hits off really well with a stranger dressed in a catwoman costume, and goes to a private room with her, after which he blacks out. Lucas says that the two had "physical contact" and Bill naturally assumes the worst. As it turns out, the "Catwoman" was Ben in disguise, who was asked by Mary to mock seduce Bill as a Secret Test of Character.
Ace Attorney:
- Exaggerated in Phoenix Wright: Ace Attorney – Trials and Tribulations. Pearl beats up Phoenix several times for his supposed cheating on Maya, even for such innocent actions like talking to another woman or looking at another woman. Made more ridiculous by the fact that Maya isn't even Phoenix's girlfriend.
- In Case 4 of The Great Ace Attorney, the landlord John Garrideb purchased a secondhand book containing a lipstick-stained note that the previous owner used as a bookmark. When his wife saw the note, she flew into a rage and started throwing several items at her husband, accidentally starting a fire and unknowingly becoming the case's culprit when a knife she threw fell out the window and onto the victim.
The Wolf Among Us: Beast is concerned by Beauty's disappearances late at night and is worried that she may be trying to hide a dark secret. When he finds her with Bigby at a seedy motel, he assumes the worst and a scrap breaks out. The truth is that Beauty has been secretly working at the front desk to help pay the rent, and Bigby is there to investigate a murder.
Cheater's Table: A non-romantic version. When the current player decides to cheat, the next player can choose to call him out. If it's a bluff, they are forced to draw 3. If it's not a bluff, then they have a 1 in 5 chance to find the cheating cards. Failure to find the cheating cards results in the accuser being forced to draw 2.

Web Animation

Etra chan saw it!: Has its own page.
Manga Room:
- Sana slapped Shota's sister believing her to be his wife cheating on Shota. She apologized to her later when Shota cleared the misunderstanding.
- Twice, Nana broke up with Ikuto in high school because she thought he was cheating on her. Several years later, she finds him walking together with another girl after they meet and talk again, causing her to hate him again. However, it's later revealed the girl was actually Ikuto's stepsister and she was also the same girl Nana saw in high school.
Sekai no Fushigi: Yuka broke up with her boyfriend Riku when her friend showed her a picture of Riku hanging around with another girl. Years later, when they met at a hospital, it is revealed that the girl is his sick sister who was in and out of hospitals and Riku had to take care of her. Once the misunderstanding was cleared up, their relationship was rekindled.
SparkTales:
- "Pregnant Wife Accused of Cheating: Husband Faces the Truth!" — Eamon suspects his pregnant wife, Lisa, has been cheating on him ever since she moved into a different room. Moreover, his refusal to accept any explanations to the contrary led Lisa to execute a plan and convene with his parents to kick him out of the young couple's house. It turns out the reason for Eamon's suspects was because he heard it from the local gossiper, Mrs. Yamada.
- "My Fiancé Stolen by My Junior Right Before the Wedding—But They Lost Everything Overnight!": Lisa's fiancé, Kira, thought Lisa was cheating on him after seeing a photo of her with a guy, which Megumi exploited to steal him from Lisa. When Kira brings it up when Lisa confronts him for cheating, the alleged cheater reveals the guy was her brother, with Mia and Noah backing her up. Even then, Kira kept excusing his affair with Megumi and blaming Lisa for her confusing behavior and not informing him of the photo.
- "Our Daughter Was Born with Blue Eyes—At a Family Funeral, the Mystery Begins to Unravel": Noah's parents tried to have him divorce Lisa by accusing her of having an affair with a foreigner because Madison had naturally blue eyes. When Noah refused to take their excuses, they gave him a DNA test kit to prove Lisa was cheating. However, even when the test confirmed that Madison really was Noah's child along with the reveal that Lisa's grandfather was a foreigner named Edward, they remained defiant and kept accusing Lisa of cheating on Noah.

Webcomics

College Roomies from Hell!!!: Subverted wherein Marsha walks in on her boyfriend Mike spanking the monkey - which is to say that literally, he has a pet monkey which he is punishing for having messed up the apartment.
Commander Kitty: MOUSE lets a depressed Ace listen in on a conversation between Freeda and Mittens, cutting off just as Freeda declares her love...for nectarines. Ace is not amused.
Cyanide and Happiness: In "The Bra", this trope is Exploited to stupid effect. A woman questions her partner on a pink bra she found that doesn't belong to her. The man (mentally reliving running around wearing the bra like goggles pretending he is a fly), nervously lies that he's cheating on her instead of telling her an embarrassing but innocuous truth.
Fox Tails: A variation occurs when the Raised by Wolves (or rather, foxes) amnesiac girl Miyo tells Keen Kotoru's childhood-friend-with-a-crush, Crystal, that she 'slept with him'. She did, indeed, sleep in his bed... while shapeshifted into a fox. The fact that Miyo habitually refers to Keen as 'Master' probably doesn't improve Crystal's view of her either.
General Protection Fault: Craig is thought to be cheating on his wife with Sharon, as Nick and Dexter spy on the two. Similarly, the German, while taking on Craig's identity during his business trip to Paris with Sharon, makes advances on Sharon, but when she rebuffs him, realizes that he has misunderstood their relationship.
"Girlfriend": The aftermath of such occurs in this short comic by DeviantArt user Murata, where the boyfriend explains that the other girl he gave a kiss to was just his sister. Then it turns out to be incest. And he had sex with her just after the kiss. And offers to let his girlfriend join and make it a threesome.
El Goonish Shive: Sarah pretends to mistake Elliot for cheating on her with Ysolda from The Elder Scrolls V: Skyrim as part of a comedic bit on Elliot and Susan's review show.
Kevin & Kell
- When Kevin and Kell are invited to The Jerry Springer Spaniel show, the showrunners try to create conflict by revealing Kevin had an online romance with someone while married to Kell. Kell's all ready to give him hell over it, until they reveal the username of his love interest...Kell's username. They end up gushing over how their online romance made their real life marriage stronger and eventually got kicked off the show for being too mushy. Oh, and Kell ate Jerry Springer Spaniel for trying to break up their marriage.
- When Bruno starts taking classes with fellow herbivores, he meets a rhinoceros named Rachel Einhorn. She is attracted to him at first sight, angering Corrie when she gives him a kiss after saving him from some coyotes and thinking he is cheating on her. It turns out that she, a lesbian, thought he (a "trans-diet" wolf wearing a sheepskin) was a sheep, resulting in him wearing ram horns with his sheepskin from that point on.
- Leona briefly suspected Carl of cheating on her with Ophelia, because her location app showed them together, but he was insisting she wasn't there. She didn't know that Ophelia was living in a burrow under Carl's gardening stadium. (To be fair to Leona, her previous boyfriend did cheat on her, leaving her with trauma around the idea.)
League of Super Redundant Heroes: This one is a gem. The worst part of it, even though the husband walks home to find his wife in dominatrix gear being tied up by a guy dressed like a gimp, it IS indeed not what it looks like.
The Order of the Stick
- Subverted here, where Nale thinks Sabine is angry with him for making out with Haley (as part of a plan to kill her) until Sabine tells him she's actually angry about the fact that he was going to kill Haley without her. She then points out that she's a succubus, literally an incarnation of illicit sex, and being faithful to one's lover is not exactly high on her priority list.
- Defied here, where Elan mentions the common story progression of him staying silent about what happened with Therkla, Haley finding out scattered hints about it and misinterpreting them, and romantic tension arising because of that... and then says "to hell with all that" and says that he feels that he needs to be fully honest with Haley if he ever expects a happy ending, even if it gets in the way of some good narrative conflict.
Penny Arcade: Used as part of a revenge plot in this comic.
Peter Is the Wolf: Peter gets knocked out and kidnapped by a long-time stalker of his. As she is about to rape him, his girlfriend bursts in, mistakes the rape attempt for him cheating on her, dumps him on the spot, and runs off.
Punch an' Pie has this happen constantly to Heather at the beginning of the strip. Her girlfriend Angela seems to think that literally every single one of Heather's friends is a possible affair. Since Angela believes that Polyamory is natural and both women are bisexual, Angela is very jumpy about Heather having any contact with anyone outside their relationship. Heather breaks up with her over it.
Questionable Content: Dora finds Marten and Faye on the couch in their bedclothes hugging and jumps to the entirely wrong conclusion. The setup starts here.
The Redemption Of Earl Nottingham: What caused Madelyn's original death — her husband's doctor has been pulling the moves on her, and her husband catches them in a compromising position. Though nothing untoward happened, Ian accuses her of adultery. She declares that she's leaving him regardless, but then falls down the stairs and dies.
Reunion (2021): In the eleventh chapter, Kori's vitriol towards Rhea is revealed to be because she thought Shiro was withdrawing from her in the last months of their relationship. She assumed Shiro was cheating, and upon seeing him buddy-buddy with Rhea, assumed Rhea was the other woman. Rhea defiantly clarifies that she had just recently reconnected with Shiro.
In Skins, Jordan walks in on what seems to be Vinnie making out with another woman. It later turned out the other woman spontaneously kissed him and only because she thought he was dead and was delighted to see him alive but Jordan was so mad she bashed Vinnie over the head with a whiskey bottle.
A complicated example in Something*Positive. Davan's ex Eva has been communicating online with her other ex, who's been pretending to be Davan to get on her good side. Then Eva spots the actual Davan having lunch with Nancy. Since she thinks that she and "Davan" are involved again, she makes a big scene. Meanwhile Nancy, rather than trying to explain that this isn't even a date, flashes her newly-acquired engagement ring and claims to be Davan's fiancée.
Almost happened in the Walkyverse, but was Averted. Danny is talking with his ex-girlfriend Sal and mentions that he is planning to ask his current girlfriend Billie to marry him.
Sal: Can I see the ring?
Danny: Hell no. I know how that works. I show you the ring, and Billie walks around the corner.
Willowyrm: When Freya demands her midwife, Willowyrm assumes Freya has said "my mid wife". When Freya demands her husband Arne as well, Willowyrm makes some assumptions:
Willowyrm: Does he know about your wife?
[later]
Willowyrm: [to Arne] I've got bad news bro. She's got a wife.
Arne: Excuse me?
Willowyrm: But pro: she doesn't seem that into her.

Web Original

A variant in this Not Always Right story. A male checking into a hotel assumes the female desk clerk is writing some sort of proposition on his keycard folder and assures her that he has no intention of cheating on his wife.
Clerk: Sir, this is the password for the Wi-Fi.

Web Videos

The McCallister Family:
- When Shawna asked her sister-in-law Jen for her honesty about why Julie would be cold to her in person, Jen's response was that Julie was either shy, insecure, or she can tell that Ty thinks Shawna is hot. Shawna is immediately offended and says she doesn't get that vibe from him at all and calls him a "dorky dad," but Jen says that dorky dads are often hot and then asks if Shawna is cheating on John. Shawna denies it because she's not, but when she admits that Ty sent her a friend request on Facebook and has asked for a meetup time at the park, Jen insists on being there. After seeing Ty and saying that he's cute, she questions Ty about his wife and her job with almost no filter to Shawna's embarrassment.
- Shawna's best friend Teeny, after Max's fifth birthday party, asks Shawna why Ty (who she calls a "hot dad") was "eye-fucking" her across the table at the party. Shawna openly denies it because she and Ty are just friends — and at the time, he was her only other parent friend. When Teeny continues to push (by saying that no matter what Shawna does, Teeny is on her side), Shawna gets upset and goes that even if Ty wanted to fuck her, she wouldn't let him as nothing is going on from her side.
- John and Shawna get into a fight when John, upset by Ty's friendliness in greeting them at dinner and Shawna being friendly back, accuses Shawna of having a thing for him. They leave their anniversary dinner restaurant early (and come home to find chaos at home with Jen and Greg not having gotten their kids to bed and Barb there causing problems). After a fight with John's mother, Shawna angrily tells him that she's insulted at the mere accusation; all she did was meet a fellow parent at the park and become friends and once again emphasizes that there is nothing going on between her and Ty. John admitted he was being an idiot about it. It was after this video that Shawna the creator ended up making a short video explaining that there was nothing going on from either Ty or Shawna's side.
- Shawna and John run into Julie while on vacation and make the stupid choice to follow her around and see what she's up to even though Shawna knows Julie doesn't like her. Shawna almost calls Ty to let him know they saw Julie but hangs up and doesn't return the call. After seeing Julie in a revealing swimsuit and then later kissing a man they don't know, Shawna finally gets a call from her mother DeeDee and while on speaker, says she saw Julie kissing another man where Ty is there to hear it. Ty, in a panic, drives out to where Julie is staying and confronts her in front of Shawna and John. The man Julie was kissing lightly was her older brother Jace who came to help out with their sick mother. Julie tells Ty what happened and reminds him why she was there in the first place, is upset that he drove out three hours one way to confront her and left their two children with Shawna's mother whom she doesn't know, and sends Ty home. After she returns and has time to think, she serves him divorce papers. While the accusation was not the last straw, the two Married Too Young and they have been going in different life directions for over a decade, with things becoming even more sour since their daughter Sasha's premature birth; the accusation was just another push to give her the motivation to serve him.
In the SuperMarioLogan episode, "Jeffy's Cellphone!", Jeffy calls a prostitute, telling her his name is Mario and asking her to touch his "pee-pee" for five dollars. The prostitute shows up at the end of the video and tells Mario they talked on the phone. Mario is confused, and Rosalina thinks he's cheating on her. After the prostitute tells Mario she's going to touch his "pee-pee" for five dollars, an angry Rosalina beats Mario up.

Western Animation

6teen: In one episode, a celebrity hairdresser comes to the mall and Caitlyn signs up for a free session, even though she's been loyal to her regular stylist for years. His high fashion styling leaves her with a bright red shaved mohawk, just when she's getting ready to go to a wedding with her current Boy of the Week. She's too embarrassed to let anyone see her, and when her boyfriend asks Jude where she is, he tells him "she's hiding because she cheated on some guy." He angrily tells Jude to pass along to Caitlyn that they're broken up. It's not until Caitlyn confronts him about being so shallow to dump her for a bad haircut that he learns she "cheated" on her stylist, apologizes, and happily takes her back.^note
The Amazing World of Gumball:
- In "The Plan," Gumball, Anais, and Darwin discover an apparent love letter from "Daniel Lennard" to Nicole reading "Your beauty and happiness is important to me," spend most of the rest of the episode drawing up an elaborate plan to stop "him," and find out only in the end that "he" is just a cosmetic brand. Notably, the children think that Daniel Lennard wants Nicole to be his mom, and the issue of Nicole's fidelity to Richard is never brought up.
- In "The Lady", Darwin and Gumball come home early to find a middle-aged woman leaving their house, and come to believe she's Richard's mistress after witnessing him apparently making love to her. In truth, said "woman" is Richard Disguised in Drag to hang out with a group of old ladies. Unlike in "The Plan", the brothers very explicitly think it's a romantic affair, getting incredibly upset while confronting their father about it—though Richard thinks they just found out about his other persona.
  Richard: Is it so bad that I have some fun? I enjoy the time I spend with my girls.
  Gumball: Girls?! Plural?!
  Richard: What difference does it make if it's more than one?
  Gumball: You maggot. How many?
  Richard: Three at the moment, but you know, the more the merrier.
Francine from American Dad! wanted to join a clique of glamorous yet snobbish housewives called The Ladybirds. A mishap at a cockfight convinced them that she could join because they thought she was having affair with somebody there. The Ladybirds turn out to be all unfaithful to their spouses.
Back to the Future: The Animated Series: In "Put on Your Thinking Caps Kids! It's Time for Mr. Wisdom!", Doc calls his memory machine "M.A.R.I.E." so he doesn't have to continually go through all the words in the acronym. When he says it while dazed, Clara slaps him. She later finds out from the televised showdown that "M.A.R.I.E." is an invention, not another woman, and says she should have known.
The Boondocks:
- The episode "Tom, Sarah and Usher" is about Tom becoming jealous of Usher when his wife Sarah meets and starts obsessing over the singer. Their daughter Jazmine even worries if they will divorce, though Tom insists that won't happen. It later turns out that Sarah was just a Fangirl and was setting up an opportunity for Usher to also meet their daughter, and never intended to cheat.
- This is repeated in the episode "Pretty Boy Flizzy", where Tom is worried that the titular character plans to seduce Sarah, who is a huge fan of his music, despite Flizzy's constant instance that he's trying to help patch up the couple's relationship. He purposefully uses the misunderstanding to goad Tom into a fight to impress his wife, which successfully makes the two's relationship better than it has ever been.
The Casagrandes: In "Let's Get Ready to Rumba", Rosa starts getting dancing lessons from a man named Ivan. Her husband Hector thinks that they're having an affair and tries to send Ivan away, but it turns out that Ivan is already married, and to a man.
The Crumpets: In "Family Secrets", T-Bone the dog brings a dug music box containing a letter to Ditzy Crumpet, who is shocked from reading the letter and interpreting it as proof of her father being in an affair. Following an emotional breakdown due to her family not helping her grounded head, she shares her rumor with her neighbor Cassandra and gets eavesdropped by baby brother Li'l One, who has a grudge on their father. After Ditzy agrees to let Li'l One present the letter to Ma Crumpet, she reads it and angrily bans Pa (who was spotted with Cassie's mother Ms. McBrisk outside) from returning home. Once Granny reveals that the letter and the music box belong to her, this rectifies the unjust punishment on Pa.
Dexter's Laboratory: While listening behind a door, Dexter and Dee Dee suspect their parents. It turns out they were playing Scrabble.
Mom: Hey, are you cheating?
Mom: Then what's this letter I found hidden in your pocket? Well?! Explain yourself this time!
Mom: I don't believe you! Passion? Passion?! Is what that letter was all about? Just so you can have passion?!
Dad: Well how about the last time I caught YOU cheating?
Dad: Hey, what are trying to do? Kill me with that thing?!
While it doesn't involve actual cheating, a Family Guy Cutaway Gag has Lois catch Peter seemingly having an erotic dream about another woman.
Peter: Oh, Jenny... Jenny... Oh, yeah, Jenny, don't stop...
[Lois sits up in bed and glares angrily at Peter]
Peter: Oh, Richard Jeni, your HBO comedy specials have brought pleasure to millions...
[Lois looks relieved and goes back to sleep]
Peter: ...And what a sweet ass.
[Lois opens her eyes in shock]
The Flintstones:
- In one episode Fred's accidental discovery of a poem dedicated to Wilma, as well as Wilma's strangely secretive behavior, make Fred suspect that Wilma cheats on him. The catch is in the fact that the poem was actually written by Fred himself when he was still a high school student, while Wilma was secretive because she wanted to surprise Fred for his birthday. It doesn't help that a man calls wanting to talk to Wilma, and she acts strangely like she doesn't want Fred to hear. He becomes suspicious and goes to another phone, to hear her say, "...that's right, Darling, not the only man I ever loved, the only man I ever will love." Fred thinks he's about to lose Wilma to another man. It turns out he didn't get to hear the beginning of the conversation, where the man said to her before she responded, "This is the jeweler calling, on your husband's watch for his birthday, you want the engraving to read 'Darling...'" It was at that point Fred picked up the phone.
- In another episode, Wilma suspects Fred of cheating, though with better cause: He's coming home late from work, unusually tired, and when she follows him, she finds him in a romantic nightclub him with a very sexy blonde. The blonde is a charm school instructor, and Fred has been taking courses in dancing, small talk, and related matters so as to make their upcoming anniversary more special and memorable. That night was the final exam/dress rehearsal.
- In a third example, both Fred and Barney fall victim to this trope when they decide to take dance classes so they can take their wives dancing. In order to cover for their classes, they join the "Bedrock Volunteer Fire Brigade", which is a front for the men of Bedrock to get away from their wives; since all buildings in Bedrock are made of stone, all fire alarms are false alarms. Once again, once the truth comes out, Fred and Barney are Easily Forgiven by their wives.
The backstory for Coldstone in Gargoyles is that "he" was constructed with the remains and souls of three Gargoyles, whom the writers fittingly referred to as Othello, Desdemona, and Iago. Iago wanted Desdemona for himself and tried to drive a wedge between the couple by convincing Othello that Desdemona was cheating on him with Goliath (making him the Cassio). This misunderstanding was never cleared up prior to their deaths, with the truth only coming to light after a computer virus destabilizes the merger of souls within Coldstone.
Harriet the Spy: In "Ole Golly in Love", Harriet suspects her nanny's boyfriend Mr. Waldenstein of secretly having an affair with Ole Golly behind the back of a "Mrs. Waldenstein", even spotting him meeting up with a woman and her baby, whom she assumes are the Mrs. Waldenstein and his child. It turns out "Mrs. Waldenstein" is actually his mother, and the lady and her baby were his sister and nephew.
In one episode of Jem Aja mistakes her boyfriend as cheating with Stormer. In contrast to most examples, she believes Stormer and Craig are married while she is the "other woman". It turns out Craig and Stormer are siblings and he was simply afraid to tell Aja earlier because The Holograms and The Misfits get along poorly.
The Johnny Bravo Christmas Episode "Twas the Night" has Johnny having to deliver Santa's presents after accidentally injuring him. At one point, Johnny mistakenly delivers his mother's present of a fur coat to the house of the Mayor of Aron City, resulting in the mayor's wife being angry at her husband because she thinks he's cheating on her with a woman named Bunny.
Justice League:
- In one episode, to prevent ex-employee Rex Mason from exacting revenge for turning him into a shape-shifting mutant, corrupt businessman Simon Stagg shows him a picture of his fiancée being tenderly embraced by his old friend Green Lantern (who was actually comforting her after Rex's mysterious disappearance). Overcome with jealousy, Rex promptly goes to attack Green Lantern.
- In another episode, Green Arrow gets jealous of Black Canary's relationship with the much older Wildcat. In actuality, the two have a father/daughter relationship since Wildcat was teammates with Black Canary's mother.
Kaeloo: In Episode 83, Mr. Cat lies to Quack Quack that Eugly has been cheating on him, making him paranoid; later in the episode, Stumpy accidentally kisses Eugly, and Quack Quack assumes that this means that Mr. Cat was right and that the kiss was deliberate.
Averted in Kim Possible. Bonnie, upset at the loss of her boyfriend, forces a kiss on an unwilling Ron. Kim catches them, and, though upset at Bonnie, she completely believes Ron's claim that Bonnie forced the kiss (because, after all, it took years for Ron to kiss her.)
The Looney Tunes Show: In "Beauty School", Lola sees a woman (actually Bugs in drag) leaving Bugs' house and getting into Bugs' car and immediately assumes that Bugs is cheating on her.
The Loud House:
- The entirety of episode "Cheater by the Dozen", which includes Lincoln and Clyde assuming that Bobby is cheating on Lori with other girls including an older woman, a man, and a dog.
- Subverted in "Butterfly Effect" — Lori finds a photo of Bobby that Leni planned to give to her, causing Lori to think Bobby cheated on her with Leni and dump him for Clyde... or at least, that seemingly happens, but it turns out to have all been in Lincoln's head.
In one episode of The Proud Family, Penny thinks that Oscar is seeing a woman named Debra. It turns out that not only was Debra Trudy's college roommate, she was also the one who introduced Oscar and Trudy to each other.
The Simpsons:
- In "Eternal Moonshine of the Simpson Mind", doubling as Out-of-Context Eavesdropping:
  Homer Simpson: I must be the only gullible husband who ever overheard snippets of surprise-party planning, and believed his wife was having an affair!
- And there was that episode where Homer and Marge were giving marriage counselling to an idol and her baseball player husband. When Homer gave the idol a backrub while eating chicken, her husband on the other side of the door naturally assumed with the moans they were making that his wife was cheating on him.
- They love subverting this. In another episode, Marge listens in on Homer in the next room with his Vegas wife (long story). She hears him says things like, "Oh that's good. Don't stop! Faster, faster! You do this like a pro!" Her response, "Oh no! She's making him a sandwich!" She was.
- In yet another episode, Marge writes a novel that has echoes of real life. Novel-Marge is unhappy in her marriage to Novel-Homer, who is a huge jerk, so she has an affair with Novel-Flanders. Everyone in town assumes this means Marge has the hots for Ned. Lisa is worried that life will imitate art in another way, since in the climax, Novel-Homer kills Novel-Flanders by harpooning him in the chest, causing him to fall off a cliff, then suffers a Karmic Death as the harpoon's rope snags him and pulls him off the cliff too. The real Homer chases the real Flanders to the edge of an identical cliff as was in the book, and Flanders closes his eyes and braces for the inevitable. Homer instead drops to his knees and begs Flanders to teach him how to be a better husband, having taken Marge's portrayal of him in the book to heart.
- It's Played for Laughs (and a little bit for heartwarming for how much Homer trusts Marge) in "The Devil Wears Nada" when Marge, whose been neglected lately by Homer's new job, finds herself almost succumbing to the temptation to cheat with Ned Flanders, but of course they realize it would be wrong and just hug at the door... just as Homer's walking up. He considers the possibility that Marge just cheated on him, even briefly gets angry at the thought, but then...
  Homer: My wife! And my worst friend!!! Could it be?! (Growls) (Beat) Naaaaaaah!
South Park: In "Insecurity", Ike sees his parents having sex while his father is role-playing, leading him to believe his mom is having an affair with the UPS man. Eventually this information gets to the other men in town and makes them think their wives may be cheating with him too.
Star Trek: Lower Decks: In "Cupid's Errant Arrow", Boimler overhears his girlfriend Barbara talking to Jet in a very Double Entendre-ish way, but he was just helping her putting a tube in a yacht at the cargo bay.
Stōked: In "Sweet, Sweet Meat Cheat", Fin overhears Reef make a comment about cheating on Lo and assumes the worse. He is actually 'cheating' on the vegetarian diet she put him on by eating franks. During that same episode, Fin running around after Reef and trying to catch him in the act is, ironically, what makes Lo herself believe that Reef is cheating on her with Fin in the first place.
The Ugly Duckling: In the Disney adaptation. the father duck mistakes his mate for cheating once he sees the titular character. The two get into a fight and he leaves. Afterwards the mother duck acts especially harsh to the swan chick.
Wait Till Your Father Gets Home deals with the suspicion of infidelity. Harry is transporting a rather attractive female client to an out-of-town meeting when car trouble forces them to stop at a motel. There's only one single-bed room, so Harry insists the client take it while he sleeps in the car. The motel manager suspects some hanky panky until he sees Harry owning up sleeping in the back seat of the car. Irma isn't buying it, believing that Harry is cheating on her. To prove his innocence, Harry drives Irma to the motel where the manager vouches for him.
X-Men: The Animated Series: In "The Dark Phoenix Saga, Part 1: Dazzled", Cyclops rescues Dazzler from being kidnapped. She thanks him with a kiss before he can react. At this moment, Jean Grey, who is increasingly unstable due to being possessed by the Phoenix and slowly being seduced by Jason Wyngarde in her dreams, walks in on them. She immediately assumes Cyclops is cheating on her and runs into Jason's arms.

Real Life

A tragic real-life example: Rush Dozier in his book Why We Hate, describes an event when a friend of his separated from his wife after several attempts at reconciliation. The man decided to call his wife before moving to another city and an unfamiliar male voice answered the phone. The man rushed to his wife's apartment (it turned out she was alone), broke down the door and fatally shot her, then himself.
Ronnie Barker was once lined up to appear on British biographical programme This Is Your Life, where a key conceit is that subjects don't know they'll be appearing on the programme until they're surprised with the famous "red book". However, his wife's sudden secretive behavior as she helped the producers plan things out caused Barker to think she was having an affair. When he confronted her about it, she was forced to come clean, and with the surprise ruined, the episode had to be scrapped. (Barker, for his part, didn't want to appear on the show anyway.)
A woman wrote to Dear Abby to complain about a mysterious young woman who was visiting her married neighbor late at night, being admitted by the husband and later let out. The woman was sure that the man was "sneaking this tart in for sex for his poor wife sleeps upstairs". Reader response suggested that the wife might be fully aware that this young woman was coming over. In fact, the young woman might even be there to see the wife herself. The responses ultimately said that the nosy neighbor was jumping to conclusions, and advised her to butt out.
During the investigation of the 2003 Superbike Motorsports murders, Melissa Ponder, the wife of victim Scott Ponder, was accused of cheating on her husband, with the police theorizing that a love triangle could have been the motive for the murders. Melissa adamently denied it, but detectives tested her young son's DNA against a postmortem sample from Scott and it didn't match, seemingly confirming an affair. However, the detectives later realized that the sample they had used for the paternity test was actually from one of the other victims and had merely been mislabeled as being from Scott; the child was Scott's all along, and all the assumptions they'd been making based on the premise of cheating were wrong. Unfortunately, by the time the error was noticed, rumors and gossip had already begun to spread, and Melissa ultimately moved from South Carolina back to her home state of Arizona to get away from the vicious rumor mill. (The case was finally closed 13 years later when serial killer Todd Kohlhepp confessed to the quadruple homicide; according to those who knew him, he had a grudge against the store because an employee allegedly laughed at him when he tried to return a motorcycle he'd purchased there.)

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