I have a couple of friends who are going through this. Exactly. I have known them both since elementary school. The guy has been in love with the girl since before I can remember and he wasn't afraid to tell her; she accepted it but never returned it. They finally got around to dating a few months ago, but she's getting bored, and shes starting to hurt him (unintentionally, of course). He has given her more chances than I would have been able to, and it keeps coming around to hurt him even more. They can't pretend that things are the same anymore (because they fight too much and can't fix things), but they can't let go of the relationship either. She's afraid she will lose him as her best friend. He's just too in love to put it behind him. As for myself, as the best friend of both of them, I wish I could fix it, but that's up to them. Everything will change.