One song that always reminds me of one particular break-up is 27 by Biffy Clyro. Even though this is really cliched, i feel like the song was written for me. What's more is that Biffy Clyro was one of her favourite bands.
Somebody made a silly little video to go along with the song, it's kinda sad but funny
But the one song i associate with all my break-ups is Untitled by The Cure. It's the perfect break-up song.