I know, I know - she seemed perfect, it all seemed like just what you were looking for - yada yada yada.
But seriously - if it was all that great, and she's running already? Either:
A) It wasn't really all that great for her,she's just a good faker, or B) She's got intimacy issues and runs when it gets close, or C) She's too much of a weenie to tell you the truth which is that her old boyfriend came back or some such
Let it go. The fantasy was nice but there's something very wrong here with the reality. Don't waste any more of your time.