Individually, I'd agree. But there was a lot going on in a short time. His youth, being newly fledged by minutes, inexperience to dealing with others of his kind, etc, all added up to him being manipulated with ease. Consider:
I think this requires a very generous reading of events. You're not wrong, but you're right in a hindsight is 20/20 kind of way.
1 - The MC drank that elixir which is giving him splitting headaches, made his nose bleed and probably making him feel disjointed as he 'awakens'. It seems to be having some sort of effect his senses and thoughts.
But his thoughts and what we are seeing are lining up completely. I can grant that he was confused, but the leap to hallucinating and thinking, "I'll just blame it on the wine", that's a extra step, and a big one.
Also, right before and during the lewd, Clair's eyes don't change, only after he bit her. There was no indication at the party that the MC was losing control over himself. He even had a calm and collected conversation with Clair about the accident. So, I think the whole "not himself" is a tough sell.
I think adding a choice could've solved this. Either the MC consciously accepts Clair's advances, or he rejects her and is given a spiked glass of water. Both lead to the same outcome, but at least the MC (and player) can hold their head high.
2 - The MC thinks he's hallucinating (People's eyes are glowing, his own are glowing and Andrew as well as John seemed to act strange) leading him feeling more disjointed.
The MC did notice Andrew acting weird, and I suspect that the MC compelled both Andrew and John, but he didn't think much of it. Instead, he's ushered away and distracted.
3 - John unwittingly played into the MC being manipulated, taunting him about seeing Monica with a strange man. Follow this with her refusing or unable to answer her phone and Alexia looking unsure while trying to reassure him.
But if I decide not to leave a message for Monica, doesn't that imply a certain trust? This MC has finished college and has been with Monica for years, and while intrusive thoughts are real, their shared history should mean something as well. Fucking a stranger because he's insecure or worried about Monica's whereabouts feels like a stretch. Things would be different if we were shown that the MC believed John or we got a mention that Monica had cheated on him before. Actual reasons that would make him doubt her loyalty and that would allow him to convince himself he earned a free pass.
The whole "she made me drink the wine, so she's responsible for my actions"... yuck.
4 - Finally, with Clair, she did influence him in the beginning, but I also suspect House Idalon have some sort of telepathy or implanted suggestion ability. There were several times during the sex scene where I felt she seemed to answer the MC's thoughts (Stop thinking why this is a bad idea...) or the MC was having intrusive thoughts that I felt were hinted weren't his.
Yeah, she did influence him to stay the night. But everything that happened in the room was agreed to by the MC, except for the last part of the
ritual. The writer has to know that this whole situation is polarizing. And, ultimately, everything the MC says or does counts as characterization. IF the MC was acting out of character, then the writer needed to make sure to convey this to the audience, and I don't think this was done adequately.
The few thoughts of it being a drug-induced dream feel too far-fetched. I didn't get the sense that he was being manipulated there as much as that he was lying to himself to avoid accountability. Yet, the first thing he does when he sees Monica is try and apologize for cheating on her, indicating he was fully aware of what he was doing. If he had been drugged and really lost his grip on reality, if he truly believed he slept with Clair because of the wine... Then he would say things like "I don't know what came over me last night;" instead of how he takes responsibility toward Marcus.
Add all that up, and he was in put into a position where he was manipulated by a master manipulator and telepath (Clair maybe the House Idalon Matriarch).
There's no doubt he was manipulated, but what I don't think gets adequately explained or telegraphed is why it worked. All the writer managed to do is make me dislike the MC, Clair, and Monica for their parts in this. They're all guilty, and I suspect this shared guilt will be the basis of their future cooperation. (I haven't finished the prologue yet)... Monica alludes to as much with "But I'm stuck with this just as much as you are."
I'm not going to say this is a bad game, or even that the writing is bad. Though, I have some concerns about the writing, most issues I have are with Part 2 of the prologue. The situation with Clair needed to be handled better. Either make it entirely clear that the MC has no agency, or hand agency over to the player and pull it away when they make the "wrong" choice. In my view of this event, the MC was a willing participant in his rape. Contradictory, maybe, but it's abundantly clear that there was no informed consent, because he had no idea what Clair had in store for him.