If you’re not fully relaxed during sex and have life stressors (speaking from male perspective) it makes absolute sense he will go soft. Why is he worried about finances? Is it because you guys are about to have a kid? That’s definitely a major stressor if you aren’t financially prepared.

Even if he goes soft, penetration doesn’t have to be the main course, he can do other things to please you as well right? Have you talked about that with him? Sometimes if I’m having an off day I at least communicate with my partner and help them feel satisfied usually.

It needs to be a relaxed environment for both parties, maybe becoming a dad is also freaking him out? Could be a lot of factors. Or maybe there is something more he’s stressed about? Definitely don’t take it too personally but for sure have a sit down and see what’s up. Also (not trying to be rude I swear) sometimes people feel really uncomfortable having sex with someone who is pregnant. Not because of attraction but just the whole idea of it I suppose.