help, please!

Alright, so I’m 29 weeks, 3 days. I went to my OB appointment and our baby is measuring two weeks ahead, putting me at 31 weeks! I recently went and seen my boyfriend (he works on the road) and I stayed with him for five days and we only had sex ONCE. I finally asked him why he was being so distant and he said, “it’s so weird having sex now. I feel like I am hurting our baby.” Is this normal or is he seeing someone else? Not to mention I did go through his phone and he created a tinder account but wasn’t smart enough to delete all of the evidence... the messages weren’t horrible but it’s still the fact he did it and he said, “I only did it because we were arguing.” I feel completely disgusting and just feel like he doesn’t find me attractive anymore.