5 Centimeters per Second deserves its own page. That movie is one of the saddest, most wretched, most beautiful things ever made, with a touch of Crowning Moment of Heartwarming at the very end, where Tohno might've had the chance to find Akari again. But she's engaged to someone else by then.
The last scene of the movie, depicts young Takaki and Akari at the same train track from the end of the movie, where Akari goes across the track but the train comes, stopping Takaki from getting across but when the train gets by, she's still there waiting while in the end Older Takaki thinks he sees her but when the train goes by she's not there anymore
As most people will point out, the whole film will reduce you to tears, but one of the most painful to watch Anguished Declaration of Love ever put to film happens about halfway through:
Kanae: I guess my wish is to be with Tohno will never come true...but I still...But I still won't be able to stop loving him. Not today, not tomorrow, not ever. I fell asleep that night crying...the only thoughts in my head being of Tohno.