IF this is a porn thing, it's come from him watching more and more depraved, and violent porn over time.
IF this is a porn thing, he is watching illegal porn, in the same way that paedophiles are watching CSA. He would be watching, and getting off on seeing the act of rape.
For him to have gotten to the point that this is even normalised in his brain as something that is OK, he has likely seen (and enjoyed seeing) numerous women be raped.
He has normalised it to the point he's said, pretend to be asleep for me.
You've tried that. You didn't like it.
He has despite you saying, you didn't like it, tried to push that boundary. Effectively saying "You do not like pretending to be asleep, I want to fuck you whilst you're drugged, unable to give consent, remove consent, know or stop me doing what I want to do, with your body"
I am concerned for you, because I'm not sure that you withholding consent is going to be a dampner on his arousal with you asleep, because thats his turn on.
I don't want to worry you OP, but this does actually happen. About 20 years ago my mums friend woke up mid sexual assault, and subsequently found there was a forum on the Internet where her husband was uploading images of what he was doing to her. There were many, many men who were doing the same to their partners. She had no fucking idea that anything had been happening.
In your position, I would be taking a very close look at this man who you married. He has a clear want to commit rape. If it isn't you, will it be someone else?
Are you safe each night? No one knows.
Are you safe having had 2 or 3 glasses of wine? Nobody knows.
Are you safe to start medication that may make you drowsy? Painkillers? Certain medications for anxiety? Certain hay-fever medications? Night nurse when you've got a cold? ...all can make you sleep that bit more deeply. Is he going to find that a turn on?
In other real terms, if it isn't you being attacked whilst you're asleep, do you know that he isn't a rapist?
At the very least, do you know if his hard drive is riddled with illegal content of women who are being raped?
On these boards, it isn't that irregular that women find out their husbands are sleeping with prostitutes to get what they want, but can't get at home. How will you know, at the very least, he isn't finding a way to do this?
In the depravity of this fetish of his, him looking anywhere, to act out his desires makes sense.
This man is dangerous OP. I wouldn't be able to trust him. This isn't even that it's you. The fact he wants you knocked out to fuck removes all personal identity, and reduces you almost to a nameless, faceless, reactionless corpse in this situation.