Thought about this too. Apart from the shock impact, many have talked about early on, I would say the game combines
1. the deep fear (and experience, therefore the life experiences folks here project onto it in a more or less controlled manner...) of being cheated on and the humiliation lying in that experiences. I would say the imagination here played out in the game has actual nightmare qualities (the scenes at the beginning are structured like that, it's the ultimate torment chamber for cucked husbands).
2. but at the same time the game offers reasons and explanations for that cheating. It opens up a space of plausible (not really imo) deniability on the side of the wife about her real intentions and her acutal free will (and many discussions here are around exactly that, some are willing to give the wife the benefit of the doubt). So we can't just brush it off with clear moral dualities of right and wrong. The hurt we feel (for the MC) can''t transalte 1 to 1 into the righteous anger of the husband who simply suffers under a frivolous wife on a drunken evening or lusting for bigger cocks. So the hurt doesn't find an easy and instant relief in moral outrage (my outrage lies deeper, not on a moral, but on an existential level so to speak). It gets pent up.
3. Like every good story it creates a scenario in which there is no good "solution" or ending whatsoever. We are put into the position of the husband narratively in that we constantly ask ourselves what should he do no how should he react?. And there is no adequate reaction. The deed and the damage is irreversibly done. Like in real life. Nothing he can do. It now becomes the story of three characters who live on but now it can only get worse (even the boss has already reached his peak satisfaction in breaking the couple I would say. the rest is repetition). We want to protest against thiis dead end but our reason tells us, there is no point.
