I'll stick to how this topic was put into context at the outset, that is, someone who cheats repeatedly.
It's wrong. There doesn't appear to be any reasonable justification for that.
On the other hand, if a person is in a totally loveless, abusive relationship and they are put in a situation where emotions are running high and they commit an act of adultury, can I say that they are just "horrible" people -- to the point, as "monkey" said of "not being given the time of day"? I can't say so.
Situations are different. People, thoughts and emotions are different. Give me an example in context and then we can make a judgement of the action and not the person.
All the same, adultury or "cheating" is not the efficacious route to take for anyone. I believe that a very high percent of the time, it is very wrong.
Tink: There is something to be said for idealism. I don't fault you and I don't think you are "ignorant."
Bradley