Help looking for a good song about why im not good enough?

ok i was trying to be with somegirl like a few days ago, and she broke up with me twice saying she doesnt know if she wants to be with me, but she says that i am the onl boyfriend who showed her any kind of affection ( weird right??), and now i feel like im i not good enough for her?? and why is it that her old boyfriends were with her longer than i was with her, even though they treated her like ****?? so yeah any good songs will help please....thanx