Pregnancy does play a part, but if the lifestyle you live with your partner isn't the one you want, that's not because of pregnancy. Have you discussed him finding a better job or going to get more qualifications?
You definitely feel more heightened emotions towards everything during pregnancy, but your financial situation needs evaluating. Why doesn’t he pay/contribute towards his child’s essentials & half the mortgage? Yes, you may earn more but you’re a team & during maternity leave, will he be able to support you both?
What made you attracted to your partner before? I think it’s the pregnancy/hormones that’s why your feeling like this. And finance I don’t think you should be taking on most of the things he should.
I would say pregnancy hormones play a huge part! My partner would give me SO MANY icks during my first pregnancy. But it does pass. As for the money side of things, maybe that needs revisiting? Sounds like you pay significantly more. What’s the percentages end up as?