To use your example, if someone perceives someone is cheating, it's usually for a reason. It may not be rational in that moment, but perhaps it is in the broader context. For example, perhaps a girlfriend gets real jealous of her boyfriend being around other girls and always accuses him of cheating, and lets assume he actually isn't. Where did that skewed perception come from? Are his behaviors suggesting something happening that actually isnt? Or, does she have a history of bad interactions that skews her perception this way? Personal relationships aren't It's not about "right" or "wrong", it's about the "why" people think the way they do. Or, said more simply, relationships don't work on a priori logic.
I should have clarified and said "if they've considered how their actions/words will impact the person who is receiving them, obviously, someone who's being mean to others has bad intentions, and should be responded to accordingly.
Moreover, in this game in the case that lead to this discussion - the misunderstanding was between someone with more social power and someone with less, and I'm generally biased towards the little guy (or girl), be it social power, economic power, whatever.