Why do I still lust after her???

Two years ago, I had a big crush on this girl, I was in gr.11, inexperienced, never had a girlfriend before. So, i saw her on the first day of school, and i started going after her, and only in second semester did I finally ask her out. She said no, she was busy. I asked her again, she said again she was going away. Nonetheless we still remained friends, as if nothing had changed.

Grade 12 came and went, our friendship deteriorated, in gr 11 we talked a lot, had an understanding, were good friends. In gr12, we hardly talked, saw each other, it was like we were casual acquaintances. Then we went off to separate unis. I've still talked with her a few times on facebook or msn, but thats about it, havent seen her in a year now.

What is bugging me is the fact that I'm not really over her. I don't feel the same as when i did in gr 11 (all i could do was think about her), now shes become just another girl but still I want to get with her. I don't know why, i don't think i like her anymore, although i admit shes very attractive. I don't think about her nearly as much anymore, just when i meet other girls, cause i immediatly compare them to her, cause she was pretty much everything i ever wanted in a girl.

Also, i keep thinking about the next time we meet up. I've changed alot since i last saw her, physically and mentally. I think she rejected me in gr 11 cause i wasnt good looking at all, repulsive actually i might say. Now i look 100 times better, i take care of my body, i dress properly and im more mature. So i keep thinking of "imagine when we next meet, im going to show her what she missed out on".

So i have no clue, am i still lusting after her cause somewhere deep inside i still like her, or because she was the first girl i ever asked out, or because she rejected me and i want to show her she was wrong, or because it was something that i was denied and I want it more/still (for me, whenever i want something, i always get it, even if it takes me months or years and no matter what it takes). Why?