I receive this question quite a bit, "Is he just trying to use me for sex? Especially when I want more?"
I think most women know when men are just trying to use them for sex–they just choose to ignore the rather apparent signs the man isn't interested in more than sex from the very beginning. These men are usually huge jerks about it and make it very obvious.
At any rate, it's good idea to spot the warning signs and if you have any self-respect as a woman, you'd be wise not to oblige a man who only wants sex because you're going to inevitably wind up feeling used and heartbroken.
You can't sex your way into a man's heart. It doesn't work that way.