Man, if you're going out with girls 'out of your league' what does that tell you? That they're in your 'league'. Accept it, deal with it and build on it. Don't live in her shadow.

Regarding the main point, I've always based relationships around sex. It's extremely important for me. If the sex isn't A+, it's not on. That's not to say I'll stick with a girl just for sex, I just mean if she's sticking around, she'd better be on my page in the bedroom.