They may be friends or colleagues but Alice and Bob care for each other, maybe each in their own way. Everyone can see it but may be thinking if they will go through with it or not, or otherwise there is not much between them to begin with. They can't be together because of different problems like family, other partners, or other circumstances.
It might happen when they're alone together, after having a drink, or engaged in some mundane occupation. Suddenly, one tells the other how they feel. Be it through direct words or subtle gestures, perhaps spurred by an unexpected revelation or heartfelt surge of emotions. This trope comes into effect.
Mistaken Declaration of Love overlaps, but there, the recipient of it is the wrong one. And like it, can be an important plot point of many Romantic Comedy bits as characters get some Character Development in order to feel or realize they have the emotional backing that makes it a hard secret to keep, especially for longer spanning story arcs.
Conversely, if a character declares this too early/late in a relationship and it misfires, or doesn't land properly, it may be reason enough for more Character Development.
If this is averted long enough it may lead to the plain old Love Confession territory — because it would be this, inverted and/or not accidental. Or, even extremes as Anguished Declaration of Love. After all, the audience may expect one of them to happen.
Because Characterization Marches On this may appear early on Foreshadowing later developments as Rule of Romantic. The "I Love You" Stigma can overlap if, for instance, there is no narrative parity between characters involved. If later, expect it to be the point of having Traveling at the Speed of Plot.
Characters will often do this in situations as odd as Twice Shy or otherwise pressed from Cannot Spit It Out. May come across as a Freudian Slip — of the emotionally charged kind and in a purely romantic sense.
It might endure Verbal Backspace or Immediate Self-Contradiction if Played With at a basic level. As well as being the single intelligible thing out from the mouth of a character that does Gibberish of Love.
For more means by which it can be accidental, it can involve eavesdropping, truth serum or inebriation, magic spells, that Noodle Incident with the Instant Messenger Pigeon.
Examples
- Bitter Virgin lead Daisuke has feelings for Hinako Aizawa. Unfortunately, the girl has been so abused by her stepfather that the only thing allowing any kind of relationship between them is the fact that Daisuke hasn't expressed any romantic interest in her. Then Daisuke wakes up from a nap to find Hinako standing over him, decides he's dreaming, and blurts out that he loves her. The incident very nearly scares her off.
- CLANNAD: Nagisa accidentally admit she's in love with Tomoya in episode 20 of Season 1 when the former's father teases her about falling in love, with Nagisa nodding in the affirmative before she realizes what her father just said, leading her to get embarrassed and her father to overreact to the accidental confirmation.
- In Fullmetal Alchemist, Winry comments offhandedly that she doesn't know why she's in love with Ed. He stops flailing around to ask her what she has just said, and she just brushes him off.
- Kotoura-san: Manabe confronts Hiyori Moritani after she tries to alienate and bully Kotoura, primarily out of jealousy. He tells her directly to her face that he likes Kotoura, unaware that Kotoura overhears this outside the classroom.
- Undead Unluck: In the Autumn Arc, while Fuuko is conversing with Andy's past self, he tells her the date of when he first awakened and knowing she's about to depart, moves in to kiss her, prompting Fuuko to say that she loves Andy's present self and it's not the time for a declaration of feelings before realizing she fully admitted that she does love Andy.
- Puss in Boots: The Last Wish: When Puss explains to Perrito how he left Kitty at the altar and how ashamed he is for it and she'll never trust him again because of it, and Perrito says maybe he should tell her how he wishes he hadn't hurt her so it might make them both feel better, Kitty is nearby and overhears the entire conversation, unknown to the two of them. Kitty pretends to just discover them afterwards, acting like she hasn't heard any of what they just discussed.
- Jerry Maguire: Jerry spends the night at Dorothy's after their first semi-romantic dinner. He overhears Dorothy and her sister having a conversation about just how deep her feelings for him are. Him being caught eavesdropping of course adds to the breakfast awkwardness.
- In Another World with My Smartphone: Touya tricks the knight Lyon into doing an accidental love confession after their cover gets blown taking down a group of thugs in the midst of following both Lyon and Olga on their date. When confronted about it, Touya counters by asking if Lyon is truly serious about wanting to date Olga since he hasn't made a move on her yet. Lyon earnestly states that he does to which Touya points out that Olga has just heard him confess.
- Wagons West: In Independence!, after a tense situation some of the ladies of the wagon train became involved in, Claudia asks Sam why he is particularly haranguing her for getting in that situation. He says it is because she means more to him than the rest do. He quickly leaves, and both reflect on what he just did... that she means a lot to him, a previously confirmed bachelor.
- In Better Off Ted, episode "Love Blurts". Veridian tries to play matchmaker for its employees, and has Ted matched with Danielle, an office worker from another office — they hit it off, even going to bed together but after the climax he says "I love you..." to her and then immediately corrects himself with "...Utah" and then cooks up a story that he in fact is from that state and is a Native-American, going so far as to create a fake Indian language. Ultimately, he tells Danielle that he lied but that he did it in order to cover up the fact that he is lonely and needy.
- The Big Bang Theory:
- In "The Wheaton Recurrence" Leonard accidentally tells Commitment phobic Penny he loves her in bed before she was ready. It causes them to break up...for the time being anyway.
- In "The 43 Peculiarity" after they've gotten back together, Penny, who has been afraid of saying "I love you" too soon due to having it backfire in the past, accidentally tells Leonard she loves him when trying to tell him he shouldn't be jealous every time she's around other guys. Leonard is touched and both nearly cry (though it's Played for Laughs) because it's such a big deal for Penny to admit it out loud.
- Frasier: In ''Moon Dance", Niles accidentally tells Daphne he loves her while they're dancing a tango. Luckily for him, she thinks he was just caught up in the Dance of Romance.
- Friends: Monica and Chandler had been secretly dating since Ross's wedding at the end of Season 4, and in "The One With All The Thanksgivings" Chandler accidentally declares his love for Monica after she sticks her head inside a turkey and does a funny dance.
- House of Anubis: After a period of Belligerent Sexual Tension, Eddie attempted to admit his true feelings for Patricia, only to be immediately shut down and insulted. However, in a later scene she wound up admitting to Joy that she has a crush on him and thinks he's cute and funny...but Can't Spit It Out. Unbeknownst to her, Eddie was listening from around the corner. This did backfire, however, as his later attempt to confront her about it led to her doubling down on her refusal to admit her feelings.
- In the pilot episode of How I Met Your Mother, Ted and Robin are on their first date. When they head back into Robin's apartment, the two are about to share a kiss until Ted blurts out, "I think I'm in love with you" which ruins the moment. His friends and later, his future kids are shocked by this, causing them to say the Big "WHAT?!" after Ted tells them the story.
- "The Mallpisode" of The O.C. featured this when Summer, Seth, Ryan, and Marissa were trapped inside the mall and Ryan and Seth tried to bust them out. Just as they return, Summer and Marissa talk about the latter's feelings towards Ryan.
- Robin Hood: When Marian persuades Robin to spare the life of the traitorous Allan a Dale in "Show Me the Money", he unconsciously says the words "I love you" to her for the first time:
Marian: Robin, please. If you love me, you will let him go.Robin: I do love you. And that's why I can't let him live. Because one day he will do something to take you away from me!
- When Elliot from Scrubs is dating Keith, she stops by his place and looks through his stuff. She finds a copy of The Joshua Tree while he's admitting his admiration for her. She says "I love U2." He doesn't know she's holding the CD and thinks she said "I love you too." This prematurely advances their relationship.
- Veronica Mars: This happened to the title character during Alterna-Prom, when an intoxicated Logan declares his intense feelings and his thoughts of their epic relationship to her and reignites a rather cooled-down relationship.
- In the Wednesday, episode "Friend or Woe", while Enid is talking to Ajax, her crush, in the antique store, she lets it slip during her comparison of a rat and a squirrel couple of taxidermied animals as working out because it would be like "Us... Them!!! Against the world...".
- Red in Gunnerkrigg Court accidentally tells "Blue" she loves her
, using an awkward Verbal Backspace to claim she was actually calling her "Ayilu".
- Bojack Horseman In "Higher Love", Bojack accidentally blurting out the words "I love you" to Wanda, and spending the rest of the episode trying to get her to tell him that she loves him back... because he's afraid of looking desperate.
- Gravity Falls: In "Into The Bunker", Dipper confesses his love for Wendy when he finds her corpse, only to learn this Wendy is the Shapeshifter and the real Wendy is standing right behind him.
- My Little Pony: Friendship Is Magic: Implied in "The Perfect Pear" when, after Buttercup ends her anniversary present song to Bright Mac with the lyrics, "And you should not blame me too / If I can't help falling in love with you", she blushes and covers her mouth. Bright Mac reveals he had been planning to tell her he loved her soon after, but she beat him to it, easing her embarrassment and taking their relationship to the next level.
- Phineas and Ferb: Isabella's crush on Phineas is obvious from her first moments on screen. The entire cast except for Phineas knows that she likes him, but she's too shy to admit it and he's too caught up in his inventions to realize it. Thus, several times, she's done this trope and quickly covered it up.
Isabella: That's not the Phineas Flynn I fell in lo— (catches herself) —into this situation with.
- Teenage Mutant Ninja Turtles (2012) has a Running Gag of Donatello admitting his crush on April via Freudian Slips. She and everyone else knows that he likes her, but she'd prefer it if they remained friends.
