I read your post and I'm sorry that you are going through that. I know what it feels like from my current experience.
I too have been married almost 7 years with 3, going on 4 young children. In the last couple of months, my wife has been pulling away, negative all the time. When this first started I tried the "over attention" route, many compliments, hugs, kisses, being super nice despite the reactions I was getting. All this got me were accusations of cheating...but that's a whole other story.
I've recently had time off work (now only part time for a few more weeks) and have been expected to take 100% of the load. Cleaning, cooking, laundry, child care, house maintenance, etc. I've done the best I can with it, and tried to stay positive. It is very difficult to stay positive however when as soon as you finish cleaning at midnight you get criticized because it is not perfectly spotless. I am getting tired of it and don't feel appreciated at all, so I do react with comments sometimes when I feel angry from this. She has even told me to put myself aside and just care 100% about her. She has told me directly I have no right to feel any emotion or be angry.
There are "pregnancy hormones", but this just seems way too excessive and irrational.
I know that she wants me to keep the kids away from her so they don't bother her. I know she expects me to do all the work, she's told me that much. I do suspect mental illness for which the doctor has told me to tough it out until the baby is born, then medication will come into play. However, I do have many of the same feelings that you have towards your husband. She did go away recently for a few days on her own to visit family and the deep down honest truth is that things were much better, smoother, calmer, more relaxed without her here. I have honestly thought that it would be better if she just stayed there and left me with all the kids. Right now she does cause more problems than she solves. I have never verbalized these things to her, but that's how I feel.
I know divorce is not an option and am praying things get better after this baby is born. I cannot live in this type of relationship, basically as a slave, I would never treat hired help in this way. There is no equality, I cannot share how I feel about anything, she can't/won't listen. It definitely can't we what God intended marriage to be.
To answer is it normal that the feelings go away... I think so, at least based on my experience. I am hoping and praying and doing my best to help them come back, but only time will tell. Perhaps there is something else going on that you don't know about and that he is too embarrassed to share. Maybe he needs to seek out help on his own.
I hope that things work out for you. I know how difficult it is and wouldn't wish it upon anyone.