Un Confession

A character who Cannot Spit It Out has finally built up the nerve to reveal a secret. This could be a life-changing event for everyone involved, finally settle the Love Dodecahedron, or permanently alter the course of the story. There's just one problem.

It doesn't stick.

D'oh!

When this happens, the audience has been treated to an Un Confession. Prevalent in series that use the Reset Button liberally, this can lead to the audience tearing their hair out in frustration. Sometimes this can be used to tell the audience something that the characters can't or don't know ahead of time, but more often than not it seems to be to maintain Status Quo Is God and Failure Is the Only Option.

May overlap slightly with Cassandra Truth, though in this case the confessor is attempting to be serious but is not believed or heard.

Anime & Manga

 * In Shakugan no Shana, the first season ends with Yuji and Shana and Shana admitting that she loves him. But come season 2? They're back to the Slap part of Slap Slap Kiss. He did hear—it just seemed so out of character (honestly, how would a real person think of a tsundere with a crush on them?) that he figures he must have been mistaken and asks for clarification.
 * Cardcaptor Sakura
 * It looked like the second movie was doing this with Sakura and Syaoran after, but it turns out he did hear it.
 * A more straight example is with Schoolgirl Lesbians Tomoyo, who tells Sakura how she feels about her, but Sakura doesn't get it.
 * Then CLAMP does this again with the Elseworld versions of Syaoran and Sakura in Tsubasa Reservoir Chronicle. This time Sakura is getting ready to tell him, but then she has all memory of him erased, and every time she tries to do it her memory of it is removed as part of "the price" paid of their relationship. Ouch. Over 200 chapters later;
 * In the Haruhi Suzumiya light novels, it's revealed that Kyon told Haruhi all about the group and its weird entities immediately after the first time she . She didn't believe him, called him an idiot, and then used his stories to cast her group in the movie she made, which explains the uncanny accuracy of the movie in summing up the cast.
 * In Fullmetal Alchemist, Winry comments offhandedly she doesn't know why she's in love with a spaz like Ed. He stops flailing around to ask her what she has just said, and she just brushes him off.
 * Amino tries to confess his love to Karada, early in the Asatte no Houkou, but is interrupted by Hiro. Their relationship goes downhill from there.

Films -- Live-Action

 * Batman
 * In the 1989 film version, Bruce Wayne tries to tell Vicki Vale that he's Batman, but he's interrupted by the arrival of the Joker.
 * Years later, in Batman Forever, he tries to announce it to the entire circus tent full of people, to stop Two-Face from releasing his massive bomb, but nobody hears him over the screams of the panicked crowd.
 * Similarly, in the 1978 Superman movie, Clark Kent starts to tell Lois Lane that he's Superman, but loses his nerve at the last minute.

Live-Action TV

 * Occurred several times on 3rd Rock from the Sun with the Solomons admitting they were aliens, though of course it never carried any consequences past the episode in question.
 * Smallville does this all the time. The eighth season alone features Lois 'admitting' to under lie detector and then claiming to have fooled the machine, and (in a separate episode) Clark . In a past episode Clark also told Lana the truth about him before resetting time after she died, and, in a strange inversion, he once erased the knowledge of his alien heritage from Chloe's mind—which also didn't stick (i.e. she remembered).
 * In the Forever Knight episode "Be My Valentine", Nick and Natalie finally openly declare their love... except LaCroix doesn't like Nick being in love with a mortal because he had to give up his love for Nick's sister 800 years ago (which somehow never came up with any of Nick's previous mortal Love Interests). By the end of the episode, Natalie has lost her memory of the entire preceding day.

Web Comics

 * RPG World literally used the Reset Button for this trope. Cherry admitted her feelings for the hero, and then an enemy attacked, Total Party Kill, Game Over. The player loaded the last save file, and all progress in their love life was lost.
 * In this strip of The Order of the Stick, Haley, seriously wounded and apparently not expecting to live, starts to . She's interrupted by Durkon curing her wounds.
 * Sluggy Freelance has Zoe "Dying" just after realizing she really does love Torg and his actions prove he's in love with her as well. Only to find out she was kept alive by nanomachines who restored her without memories. Then comes Riff who time travels to the night before she "dies" to copy her memories making her revelation never happen.

Western Animation

 * Played for Laughs several times in Family Guy. In keeping with the show's increasing reliance on shock value, it normally involves Peter being a total Jerkass when inappropriate, or Lois admitting to some past (wild) indescretion.
 * In Phineas and Ferb Across the Second Dimension, it is revealed to the main characters that their pet platypus Perry is a Secret Agent. By his organisation's rules, this means that he'll have to move to another family... unless their minds are wiped, which the family agrees to. This isn't where the trope comes in. It's where Phineas's love interest, Isabella, kisses him just seconds'' before their memories are erased, to take advantage of the trope.