It sounds like you are in a similar situation to what I just got out of. I had been interested in a girl, and she knew it, but she didn't want to be more than just friends. So I broke it off entirely. We don't even speak to each other now. The best (and hardest) thing to do is just let it go. Never admit that a girl is too nice, or too good, or too hot, or too whatever for you, because chances are just as likely that the opposite is true (meaning YOU are too good for HER). If she can't recognize that, she really isn't worth it.