If a guy gets cold on ya only after a few weeks just write him off. It's possible not having sex was a deal breaker, because to "some" guys that is the only purpose for having a relationship. If feelings come along later that's fine, but if they don't whatever they are still getting sex.
It's been only two weeks, that's not enough time to be worried about it. If it's sucking, look for another guy that is worthy of your time. Who knows maybe he's found a new interest and is seeing if it pans out before dumping you.