This is a really great post. For half of it, I could see what had happen in my last relationship but the next part didn't match at all. The timeframe was incoherent. I'd be glad to hear what you think about this problem.
You get the girl relatively easily, go out with her a few times, **** her 2-5 times, nothing seems wrong, and then SUDDENDLY, she starts exhibiting the pattern you describe, i.e. she doesn't want to get that much with you.
I do not know if this is a reccurring pattern that many have seen, but I believe it's simply that there was an animalistic connection between the two of you and then, either she or you realised you weren't interested in a relationship. Sounds like she wasn't. What's interesting for me is that I wasn't much either...