There is no such thing as a "perfect girl". I don't think love can be explained at all. In fact psychologist Marianne Williamson has a great line in her "course of miracles" talk. She says that if you found the PERFECT partner, good looking, charming, smart, rich, social, kind, respectful, blah blah blah...then think about it, would S/He want you ? It's actually very funny, but also very true.
Mind you, the guy I want is very good looking, and I'm sure most of the other things to, but I'm also sure that he ISN'T perfect, and you know what? I'd hate it if he was. In fact...I thought he WAS PERFECT 20 years ago, and that terrified me. It created so many hang ups it was unbelievable. I thought I was too stupid, too fat, too old, too everything. Mind you, I think the reason I thought that was because he gave me the message that I wasn't that important. I wasn't a priority of any shape or form, so this triggered fear for me. I figured if I wasn't that important, then he'll definitely see all my faults.

It would have been a totally different story had he made me feel like I was worth bothering with, but he didn't. I now know why, but didn't help me 20 years ago.
Hmmm, that's sad. There is nothing anyone can say to remove that. Telling you to get over it is useless. Well, see how you go with the new girl. That's all you can do. Of course...you could always wait a few years, then go find the ex again. She might've grown up by then. Just a thought.