I want sex but I don't.

So I'm 27w and 1d pregnant and here lately I have been wanting sex but at the same time don't really want it. It makes me feel crazy like I'll initiate it with my husband and then we'll be having sex and I just want to stop. I of course keep going for him but deep down inside I want to stop. Does anyone else have this issue and if so how do you deal with it?