I'm Crying but I Don't Know Why

A character spontaneously starts crying, seemingly for no reason. When asked about it, even they don't know why they're doing it. There is inevitably a plot-relevant reason behind this.

Perhaps it's a repressed memory that has just been triggered, or maybe something bad has happened somewhere else and their Spider Sense is tingling. Whatever the reason, it's usually because their subconscious knows something that the conscious mind doesn't.

It is particularly likely to happen if the character is The Empath or has a Psychic Link to someone else. Another common variant involves a loved one that was somehow erased from existence.

For the nasal equivalent, see Sneeze Cut. Sub Trope of My Significance Sense Is Tingling.

For characters who are just confused because they didn't know they were capable of crying, see My Eyes Are Leaking.

Anime and Manga
"Sophie: I'm sorry, Heen. I know I need to keep running. I just can't seem to stop crying, that's all."
 * This happens in the end of Kannazuki no Miko; then Himeko, after her love Chikane is erased from existence, (including from Himeko's memory) looks at pictures that used be of her and Chikane, but now are only of her because of the erase, she starts to cry and she does not know why.
 * In Scrapped Princess, Pacifica starts crying when her is killed elsewhere, even though, due to a case of Laser-Guided Amnesia, she doesn't have any memories of him anymore.
 * In the Karin manga (not the anime), Karin's vampire family removes all knowledge of them from her mind, so she can live happily without their burdens on her shoulders. When Kenta (who knows about the memory adjustment) asks about her family, Karin starts crying, but she doesn't know why. Cue Kenta's marriage proposal to Karin.
 * Rei does this on two occasions in Episode 23 of Neon Genesis Evangelion.
 * The first is after her conversation with the sixteenth Angel after it forces her to feel sadness. It's not that she doesn't know what sadness is, just that she's actually feeling physical manifestations of emotion.
 * The second is after she . She feels sadness, but she doesn't know why.
 * In the movie of Howl's Moving Castle, this is implied to be the reason Sophie cries as she

Comic Books

 * Justice League of America: After their attempt to conquer earth fails when they are found vulnerable to fire, the fifty White Martians,face the Martian Manhunter. At the end, the narrator tell us of a man that, every morning just after awakening, feels like he had once incredible power that is forever lost. This feeling of loss and frustration is shared by other fifty humans scattered in the earth, and is so big, he wants to cry. But he doesn’t, because he is an adult and has no time for such nonsense. So he smiles, goes out and begins his working day as a fireman.

Film

 * In Star Trek Generations, Data cries when he finds his beloved cat Spot unharmed in the wreck of the Enterprise D. Not understanding why he is crying in spite of this event making him happy, Data assumes that his emotion chip must be malfunctioning. Deanna tell him that it's working just fine.

Live Action TV

 * Amy Pond does this in an episode of Doctor Who..
 * It happens to Amy again in the Season Finale
 * On Lost, Daniel cries while watching a news report about the Oceanic 815 crash. He says he doesn't know why.
 * On Friends, Phoebe goes through rapid mood swings later in her pregnancy. When she goes from hysterically laughing to bawling her eyes out, she just says "I don't know." in response to Rachel and Monica's concern.

Video Games

 * Happens often in the Kingdom Hearts series from Chain of Memories on, usually a character crying because of something they can't remember or a link to another character.
 * Also in Dream Drop Distance, when
 * In Fire Emblem: The Blazing Sword, if you fulfill certain requirements you'll get a secret gaiden chapter in Hector's route. After Nergal's defeat, if you unlocked that chapter.
 * At the end of Lufia II Rise of the Sinistrals, Tia, who previously had been Unable to Cry due to overly toughening herself since childhood, suddenly finds herself crying uncontrollably without knowing why..

Webcomics
"Student: Why are you crying, Dr. Physics Professor?
 * Played for Laughs in El Goonish Shive, after Justin encounters a creature seemingly made of fire that doesn't burn. Cut to:

Professor: I... I'm not sure..."

Web Original

 * This is the premise behind the Somewhere An X Is Crying trope names.