In general her songs are about a boy that she had a crush on, or someone she broke up with, but in the song knew you were trouble I heard it was about her. But some of her songs are about friends and family, fifteen was about her friend going through high school, with her.
One of her last 100 bf's I guess. You'd think as many guys as she dates she would've figured out by now that she is choosing guys that treat her poorly. I hope her next song isn't about dating, it's getting redundant in my opinion. Learn from your past mistakes T.S.