Basic Trope: A woman finds a piece of hair on her husband's clothing, pillow, etc. that is obviously not her own (e.g. longer or shorter, different color, different texture, etc.) that indicates her husband is (or at least may be) cheating.
- Straight: Alice is doing laundry, and finds a long, blonde hair on Bob's jacket. This indicates to her that Bob is cheating on her; where else could that hair have come from?
- Exaggerated:
- Alice finds a lot of hair on Bob's jacket. Turns out Bob has a shedding Cat Girl for a mistress.
- Alice finds a wig.
- Alice finds a pubic hair.
- Alice finds a hair and has it forensically analyzed. She then discreetly gathers hairs from various female neighbors, friends, and coworkers to compare with the sample strand.
- Alice finds a male hair (how she even knows it belongs to a man is a Riddle for the Ages). When Bob comes home, he is greeted at the door with Alice shrieking various homophobic slurs at him.
- Downplayed:
- Alice finds a hair on Bob's jacket that's a slightly different shade than hers, but could have come from him, maybe. She needs more evidence.
- Alice finds the hair but considers the possibility of innocent explanations, such as a simple brush by.
- Alice and Bob have agreed to allow each other to have discreet liaisons. When Alice shows Bob the hair, her only problem is that he is not being discreet.
- Justified: Alice needs evidence before she goes off accusing her husband of cheating on her, and an obviously foreign hair strand can be a good indicator.
- Inverted: Bob really is cheating, but Alice is in denial about it; when she finds a strand of his mistress' hair on his jacket, she makes up a bunch of increasingly implausible alternate explanations for it.
- Gender-Inverted: Bob finds a blond hair on Alice's jacket.
- Subverted:
- The hair found on the sofa belongs to their neighbor, Claire, who sat on the sofa during the Super Bowl party last night.
- Alice takes it as an indicator that she's going gray and panics about that.
- Alice finds a hair, but it's from their long-haired cat.
- Double Subverted:
- It turns out that after a few too many beers, Bob and Claire did it on the sofa when Alice was out of the room.
- It turns out Bob is cheating with an albino girl.
- Alice compares the hair to the cat, and it is not a match. It turns out it really is from Bob's mistress.
- Parodied:
- Alice carefully checks Bob's clothes for hair but doesn't find any. She concludes that Bob must be cheating on her with a bald girl.
- Alice finds a blonde hair on the bed while Bob is in bed...and discovers it's still attached to Claire's head, Claire herself being completely nude next to Bob. Bob insists that he was not just having sex with Claire, and they did not stop two minutes and fifty-two seconds ago when he heard Alice come up the stairs after taking the cookies out of the oven.
- Alice jumps to the conclusion that the hair she found is an indicator of Bob seeing another woman, but then remembers that it's her hair.
- Alice mistakes the hair for a strand of her own.
- Alice finds a spaghetti noodle strand in Bob's hair, and Alice deducts that Bob is cheating on her with the Flying Spaghetti Monster.
- Alice smells whiff of perfume that isn't hers, lipstick on Bob's collar, a used condom in the trash after weeks of Bob "working late" on an almost nightly basis, and unusual charges on her and Bob's credit card. She still suspects nothing is amiss. On the way back from the grocery store and dropping the kids off at practice, Alice passes several billboards with messages along the lines of "Is He Cheating on You?" and movies about cheating, and a skywriter writes, "Alice, Bob is cheating!" in giant letters the whole town can see in the sky. And she goes to the doctor for burning and unusual discharge "down there," which the doctor straight-up tells her is from an STD, yet Alice hasn't had sex with anyone other than Bob in years, if ever. Yet Alice still doesn't think anything is wrong until she finds a strange hair.
- Zig Zagged: Alice finds a long, blonde hair, and accuses Bob of cheating... But Bob isn't cheating at all, proves it, and Alice apologizes. But it turns out she knew exactly who the hair belonged to the whole time, as she's the one who's been cheating, and just accused Bob so he wouldn't suspect that Alice was sleeping with another woman.
- Averted:
- Alice doesn't find any evidence (real or just perceived) of Bob's infidelity (whether or not Bob actually is being faithful or is just good at getting rid of/hiding evidence is another matter entirely).
- Bob isn't cheating at all.
- Enforced: The hair serves as a Chekhov's Gun, or at least a MacGuffin, in a Chick Flick.
- Lampshaded: "This isn't my hair!"
- Invoked:
- Alice suspects Bob of cheating, so she carefully searches Bob's possessions for evidence.
- Claire leaves hair on Bob's coat to break up Alice and Bob.
- Alice plants the hair herself so the divorce courts will favor her.
- Exploited: Alice doesn't mind Bob's infidelity, but Bob has a reputation at stake. She decides that it's the perfect opportunity for some Blackmail.
- Defied:
- Bob *is* cheating, but carefully destroys or gets rid of any evidence; he uses a lint roller to remove any foreign hairs from his clothes.
- "There's a thousand possible places this hair on Bob's jacket could have come from; assuming it means he's cheating on me would be insane."
- Discussed: "Bob! Whose hair is this on your jacket?" "This isn't a chick flick, Alice. Do you know how many people I bump into on the subway every day?"
- Conversed: "Oh look, she found a hair. I haven't seen this a million times before."
- Implied: Charlie and Deborah are discussing why Alice and Bob seem to be drifting apart lately. Deborah notes that Bob's jacket was kind of dirty yesterday.
- Deconstructed: Bob may or may not be cheating; Alice has driven herself crazy and ruined her marriage, and has no evidence besides the hair that anything actually happened.
- Reconstructed: Alice and Bob eventually get their lives back in order, and mature as people. They may even manage to save their marriage, and become a stronger couple.
- Played For Laughs:
- Alice finds a hair on Bob's clothes and thinks Bob must be cheating on her, then remembers that she dyed blonde last week, so this is actually her hair.
- Alice grabs the Idiot Ball and mistakes Bob's hair for Affair Hair.
- Played For Drama:
- When Alice confronts Bob with the hair (or other evidence), Bob admits to cheating. They either decide to end the marriage, or attempt to salvage it (but whether they do or not, their relationship will never be the same).
- Alice goes on a Roaring Rampage of Revenge, but not against Bob (bonus points if it was a case of Mistaken for Cheating).
- Alice had multiple reasons to suspect Bob of cheating, such as coming home late and showing general disinterest in their marriage. It's the hair that confirms that the affair was with her best friend Claire, who Alice confided with about her suspicions, and assured her that Bob would do no such thing.
This isn't my hair!
