Not Showing Enough Affection Toward SO While Pregnant

My SO and I have been together for 7 years. Our son will be 2 years old in August and I am 18 weeks pregnant with Baby #2. We do not live together but me and our son stay with him on the weekends.

He has been really upset lately because he wants to have sex and I don't feel good most of the time. I feel exhasted, stressed out, and uncomfortable more often during this pregnancy than the first. I'm not usually in the mood to have sex or do anything sexual. I just want to hangout and spend time together and cuddle and things like that most of the time. He gets really upset and argues that I never show him affection and that he feels unwanted or unneeded. He asked for nudes earlier today but I was watching our son outside when he was on the swing. My family was with us and he thought that they would watch the Baby and I could tell them I had to go to the bathroom and take the pics. I would have had to leave him outside with my younger sister and instead told him I will send them tonight after our son falls asleep.

He called me saying he was tired of waiting all the time and that I never send nudes or initiate sex. I'm never in the mood and argued that I get upset about him watching porn but acted like the reason he does it is because of this. He said what's the point in me even sending them when Baby is asleep because he'll already be asleep and won't see them till morning when his mind is "where it should be (on work) instead of on me"

Is it odd that I feel like I don't want to have sex all the time or that I don't even think to try to initiate sex, send nudes, or anything anymore? I don't know what to say or how to explain to him