Maybe because he had a miscarriage the firt time the doctors don't wanna have any risks taken this time round. He is with an extreamly dominant alpha so maybe changes things as well with him having a weaker body as is.
I think he’s just being overly cautious because of what happened last time and what the doctor said. And you shouldn’t have sex at the beginning of pregnancy anyways. But he is 5 months so it should be okay.
Why are they abstaining from sex? You can have sex while pregnant it's not bad for the baby or anything