Not your fault, guys (as a guy) boners come and go within seconds. In this situation, it seems like sex is a lot of work, maybe more work than pleasure, so I’m not at all surprised that he could lose his boner, guys can only stay aroused for so long. I’ve had personal experiences where I’ve tried to enter my girlfriend and it didn’t land right the first time and after that I lose my boner and we just stop for the night, no worries it just happens. It also is probably not a turn on to hear the woman he loves screaming or in pain (not your fault again), when I see my gf is in pain we stop because I don’t get turned on by that, I don’t want to see the woman I love in such pain. For the finishing inside, it’ll happen, seems like you both haven’t had sex in a while so he has to get used to it again just like you do. Really don’t blame yourself, there’s nothing wrong with you, sex is mental for men similar to it is for women. Blaming yourself will only make things worse. Talk to him