Cheating is unnecessary. Find someone who shares your values instead of lying to yourself or your partner. Then this wouldn't be an issue in the first place.
Also, in another comment chain you made a statement about monogamy being unnatural. So, what if it is? There are plenty of societal expectations we have that go against human nature that most people would agree are beneficial. For example, fighting is a basic human instinct. It's done to assert dominance, protect or vent frustration amongst other reasons. This can be even noticed in animals. But, in our society the expectation is that you restrain yourself instead of becoming violent. Unnatural =/ bad.
Just some food for thought.
I acknowledge that societal dating pressures exist. That being said, claiming that individual preferences are illusionary trivializes individual preferences altogether. Whether or not the preferences comes from a societal pressure, doesn't mean its invalid. If anything, believing otherwise can be dangerous. For instance, if a woman doesn't wants kids, that's not necessarily a bad thing. Claiming that they're wrong because there's a biological desire for humans to reproduce would be obnoxious.
That's all to highlight that others individual preferences should be respected. This includes both monogamous and non-monogamous preferences.
As for the comparison between fighting and romance I made, it wasn't to claim that these two things are similar in substance, rather I was saying they're similar in origin.