I really like immortal's response.
I am a woman and had similar issues. What I am talking about is I had fantasies that I was not sure my husband would be down with and was a little embarrassed by it. I also kind of felt like he was doing more sexually and was expecting things of me in return. Which he should. But I don't deal well under pressure to 'perform'. It was easier for me to keep my little fantasy to myself and take care of myself alone. I have talked about it with him since then. He didn't react how I thought he would and is willing to work with me on my fantasy thing to an extent. If this is what's going on though it would be best to let him bring it up. I wouldn't have wanted to tell my husband about it before I felt ready. Like a few of the posts said maybe you are coming on too strong and he is intimidated. You set your standards so high and maybe he just wants a quickie every now and then.