Completely understand where you're coming from, but I also find it frustrating that 99% of NTR games make actual NTR happen as a bad ending, dark route, etc... In other words, as a BAD consequence for choices that are, according to common wisdom, bad choices. Truly, almost all games go that way... It's commonplace.
Bearing in mind that I don't intend to pass judgement on this game, for the sake of discussion I'd say that as long as it's not ONE PATH = ONE ENDING, I wouldn't mind that one of the consequences of the unfaithful path be a bad ending, or multiple bad endings, with separation being one of them, the MC ending like a broken cuck being another, etc. But I would disagree that such endings have to stem NECESSARILY from unfaithfulness in a relationship. I don't believe that "crime equals punishment" is a good enough motive to invest time writing a story around.
I'm really looking forward to finding a game that deals with this in a more complex way. A game where characters don't readily accept all broken boundaries, as if they were made of marble rather than flesh and bone (and ego) - which is sometimes what sharing/swinging games seem like; where they get really pissed off, fuss about it, take action on it, but also where they can come to an understanding, despite the storm, restore their broken trust and rekindle their love, realising, perhaps to their surprise, that what they feel about each other matters more even than your shattered imaged of their integrity and trustworthiness. And, perhaps, that fixing things is a project and takes some effort, rather than just making another promise.
As long as there are valid actions/options the MC can use to steer through the turmoil, I can see different endings coexisting without losing the idea that actions have consequences.
What I mean, in short, is that I don't like conceptual moral rules, but that doesn't mean I rule out morality altogether. If the story is built in such a way that you have to be an egotistical maniac to make your wife cheat on you, then by all means, let there be pain and gnashing of teeth for you. But if it's possible to get there while the MC is still invested in her and in their relationship - because of impulse, or miscommunication, or even a bout of egoism in what could mostly be considered a mutually respecting relationship - I'd love to see how they'd fuss and fight, and then end up looking again at each other and hoe far they've come, and realising how everything else is relative.
I'm probably being idealistic. From what I gather, some people here actually lived relationships with some elements as what we're discussing... I haven't. Probably 90% of human beings would react in one way or another, and I'm likely one of them. I have no idea if I could in real life deal with betrayal in any other way, but isn't that part of what games/stories are for, to read about and think about what you're not experiencing in your day-to-day life?