He finishes and I'm left...

It's not that I don't want to but, lately my s/o wants to have sex and I say okay but don't really want to. Reason being is that he doesn't even try to get me started. He just goes for it, finishes, and that's it. We go to sleep or continue to do what we were doing. And I'm left not even wet or half way. The other day I start off by giving him a BJ, then he turns me around and finishes. And that's it. Didn't even try to get me going or do anything. It's been annoying and I'm too shy to say anything to him. But it's frustrating that I pretty much have to wait until it's my turn to come too. It just kills my mood of wanting to have sex. Should I say something to him? What if he gets offended that he can't make me come.