>>18658708 (OP)
If a woman has sex with you on the first date, it's because she actually really likes you. I speak from experience. Girls that don't actually like me won't even text me after I give them my number.
The times I've even had sex at all were with women that did it the same night with me we first hung out. One of them even made it a point to tell me she doesn't just do that with everyone.