For people who are embedded in a social structure, it can be costly to step outside of it. Many people will justifiably choose monogamy simply because, given the equilibrium we’re in, it is the best move for them...even IF they would prefer a world of polyamory or some other alternative.
To go off topic for a moment, the same could also be said of religious belief. I know the people here feel a special allegiance to the truth, and that’s wonderful, but if we lived in 12th century europe it might not be worth rejecting religion even if we saw through it. For that matter, people in the modern day who are particularly entrenched in a religious community...may wisely choose not to even think about the possibility that they’re wrong. Wise because, taking this equilibrium behavior as given—accepting that no one else in the community will seriously consider the possibility of being wrong—means that deviating will be scorned by all the people whose opinion the deviator cares about.
I applaud people who are devoted to truthseeking, but I do not condemn the rationally ignorant, or for that matter the people who choose to be monogamous simply because that’s what society expects of them, rather than because it’s “what they really want” or “who they really are.”
You shouldn’t take this post as a dismissal of intuition, just a reminder that intution is not magically reliable. Generally, intuition is a way of saying, “I sense similarities between this problem and other ones I have worked on. Before I work on this problem, I have some expectation about the answer.” And often your expectation will be right, so it’s not something to throw away. You just need to have the right degree of confidence in it.
Often one has worked through the argument before and remembers the conclusion but not the actual steps taken. In this case it is valid to use the memory of the result even though your thought process is a sort of black box at the time you apply it. “Intuition” is sometimes used to describe the inferences we draw from these sorts of memories; for example, people will say, “These problems will really build up your intuition for how mathematical structure X behaves.” Even if you cannot immediately verbalize the reason you think something, it doesn’t mean you are stupid to place confidence in your intuitions. How much confidence depends on how frequently you tend to be right after actually trying to prove your claim in whatever area you are concerned with.