This is not a cop out. It's a fact. If someone is not in an "active" relationship with another then there is no NTR or cheating or whatever you want to call it. Seriously look it up.
I agree. You can definitely get cucked by a woman.
Frankly, neither do I. Because it definitely IS a thing.
But as I said. "IF" I decide to let them continue once they ARE in a relationship with the MC then it will be optional. (i.e. Avoidable at that point). But to be honest I doubt I will be, 'cause frankly I'm not into that either unless it's in a threesome (or more) environment with the MC.