I think it's because it's the unofficial translation, but I hope the official translation ...

I think it's because it's the unofficial translation, but I hope the official translation does relay how much of a sickening feeling you get from the way he words his sentences. This scene in the novel was so fucking manipulative. He knows exactly how to play on Michelle's guilt and emotions, and his feeling of loyalty and duty so even if he's hurt and betrayed by the lie, he's not fully processing his emotions because he's at war with being relieved he's not going to part with "Ain" but at the same time shouldn't he feel lied to by "Ian"?
At the same time, he prepared himself mentally to accept whatever Lord Sheleg js like to begin with as long as he's amicable and not abusive, and that he'll dedicate himself to him. He's been groomed (in the traditional sense) and raised to be "demure" and loyal and a traditionalist conservative, and so he still feels it a duty to please his "wife" and foster a harmonious marriage, which clashes with his mental and psychological need to process hurt and anger and betrayal, and what Ian does is press further onto those parts of him and his emotions to pressure him, all so he can observe WHEN Michelle finally cracks and starts showing his true ugly and angry and unfaithful side that is uninterested in him now that there is no power dynamic placing him above Ian and he's no longer the one who's looking down at him.
And I say "when" because to Ian's mind it's not an "if". He's wholly convinced that's the reason why Michelle isn't reacting positively, which also isn't something he didn't expect. He planned this whole scheme with the expectation of such a reaction just to prove to himself that all nobles are trash manwhores who exploit whoever is of lower status, but that's a whole ass lore dump about his past you'll have to learn as the story progresses.

It wasn't until Michelle started spouting shit like he'll never abandon him had he been a woman and got pregnant, and running away with him, and even earlier when he kept talking about how he'll always be faithful because that's how his parents were and his father never had mistresses even if it's normalized in the south, that Ian took further interest in Michelle to keep the game going. He truly was planning to kill him that day in the snow while they hunted. He was being fr when he informed Katya that they shouldn't prepare anything. Michelle wasn't meant to return from that stay, and his return doesn't signify more than Ian's intrigue to see how far he can push him to finally roll over and show his ugly rotten belly of noble mentality and trashiness.

Thanks for coming to my ted talk. Prayers for poor Michelle who's being thrown around like a ragdoll in Ian's schemes of self hatred and self flagellation justification.