@LadyMarissa “By definition, cheating is a physical affair in which a male & female engage in sexual activities outside their primary relationship.”
This isn’t even remotely true. There’s no such thing as cheating in the absence of rules because what counts as cheating is defined by what rules exist. This is the case whether we are talking about basketball, chess, or relationships. And the only ones who get to decide the rules of a relationship are the people who are in that relationship.
You are also assuming two other big things that aren’t true. First, by saying that “cheating is a physical affair in which a male & female engage in sexual activities outside their primary relationship,” you are assuming that relationships (and cheating) are defined by heterosexuality. But it’s still cheating if one member of a gay couple has sex with another person of the same sex without permission even though it isn’t a case of a male and a female.
Second, you are assuming that everyone treats a particular dyadic relationship as primary. Some people who are in multiple relationships don’t recognize one relationship as primary over the others. And some people who are in multiple relationships do prioritize one relationship over the others, but the one they prioritize is not dyadic.
At the end of the day, fidelity is a matter of adhering to the promises you have made to your partner (or partners)—regardless of whatever promises other people have made to their own partners. Unless they overlap in some way, the parameters of my relationship cannot determine the parameters of anyone else’s relationship (and vice versa).