Pregnancy, sex, and cheatering

So I'm needing advice cause I'm not really sure how to handle the situation I'm in. My SO and I have been together for almost two years (June 1st) and with our first child due not to long before then (March 14th). Lately it seems like he hasn't been attracted to me for the past 3 weeks basically at all. I'm in the last month of my pregnancy and I feel huge, but I honestly haven't gotten THAT big. I asked him earlier today what his deal was, and if he was just waiting until after the baby to do anything and he said yes. I'm not saying he's predictable but I've caught him talking to another girl while we were on an "sex break" about a year ago. Should I be worried he'll do it again, should I confronted him about my concerns? Idk what to do.