And if we go to an extreme, that you operate solely on your wiring and nothing else... well, you're hardly a modern human at that point.
...one of those abilities that make humans as a species noble.
When did residing in a particular nation-state define such specific moral boundaries? Are you saying if I move to China I can cheat on my spouse because that's how things are done there? It seems you are applying your own morals to 300 million members of a very diverse group of people.
So I'll only make the general claims for Americans.
Judge all you want, but if it ain't illegal don't shove your values down people's throat.
Having multiple relationships, known to all parties is subjectively wrong and we can argue about it as much as we want.
Agreeing to a monogamistic relationship and secretly breaking that agreement, as implied by your use of the word "cheater", is objectively wrong.
If the alternative is to break up a family so the cheater can be 'honest' with him-/herself, is a lie and a happy family worse than a broken family? Stop seeing things black and white.
And I can understand specific contextes, so don't come up with things like "what if the other is handicapped".
But it's ok, you place value in peace of mind, I place value in respect, different points of view, nothing new, no big deal.
- If someone wants to believe the lies, then in order to avoid discovering the truth, they will keep the relationship intentionally superficial.
- If someone doesn't want to believe the lies, they will discover the truth sooner or later and they will just be acting through life.