sex during third trimester

I'm 34 weeks and since my bump has shown my husband refuses to have sex. He thinks he will hurt the baby, obviously I've explained to him how the human body works but he still just finds it too weird. So, a few weeks of us not having sex caught up with him last night and we ended up getting it on. Obviously, with a huge bump it's hard to do it like we used too. He usually likes to throw me around in different positions so we had to do it so it was comfortable for me. 
We tried a few positions, from the side, me on top and missionary. At first it was amazing, I felt us really connecting again after us not having sex for so long. Then he had trouble cumming, don't get me wrong his dick was hard but he just couldn't cum. I tried everything! He ended up just giving up and we went to sleep. This morning I ended up jumping in the shower with him and giving him a blowjob, he managed to cum then so that made me feel better. 
I just felt so unattractive because I couldn't make him cum last night,  sex before pregnancy was so effortless we just connected like jigsaw peices. I don't think some people realise that pregnancy can really put a strain on your relationship.