Sex has become rare and rather boring...

So, me and my partner have one child and one on the way. Lately sex is almost nonexistent, and when it does happen it’s all just to satisfy him and then that’s it done. I’m quite a sexual person, I’m open to trying new things tend to have a high sex drive. Throughout both pregnancies my sex drive has increased even more so. So you can see why I’m frustrated this time around when I’m not getting my needs met. He’s convinced I’m going to get elsewhere to satisfy my needs (which I would never do) but him saying that just makes me think he’s doing that to me.