12 weeks pregnant, fiancé can't finish, I cried

I'm 12 weeks pregnant and my fiancé and I haven't made love in almost a couple weeks and tried to last night but he couldn't finish because it felt different in there and was worried that he might hurt the baby. I cried because I felt like I don't make him feel good anymore and that there might be someone else that's making him feel good. I asked him that and he swore there is no one else, only me, it just really felt different in there and worried that he might hurt the baby.. So do you ladies have had the same thing happened where your SO can't finish because it just feels different inside since you're pregnant? And is it normal that guys just can't finish sometimes? Or do you think he can't finish because there is someone else that's making him feel good? I want to know what you ladies think and what I should do because this is driving me crazy!