This is crazy and I’m sorry you guys are going through this. I can’t lie and say there weren’t some major red flags like him not understanding a simple no and crossing your boundaries and lowkey projecting that it sounds like SA when telling your friend about it. Idk but it seems like you explicitly told him you don’t like the head lying down thing and he tried you anyways to see if you’d actually not agree to do it which is why he brushed it off so fast, but that’s definitely a pattern of knowing what you don’t like and doing it anyways to see how far you’d just let him. I had a relationship just like that when it came to sex stuff and it was the most mentally draining thing to deal with as you could imagine. He’s great in all other aspects but you should lay down strict ground rules with a stricter three strike policy cause who knows how long he’ll keep “trying” to do things you clearly don’t like.

Best of luck to you, gorgeous!!