The big question in first-year psychology is: is human behavior determined by genetics or context? The answer is, basically, a bit of both, so I've just saved you four years of a degree.
If we apply this to monogamy, things are a bit different. We can observe that in the animal kingdom, it's more of an exception than a rule. Beyond a few species – penguins have gotten all the fame – the ways of bonding are extraordinarily diverse. Humans are not exempt from this diversity either, although we often act as if there's only one right way to love.
And this is where I think it's worth pausing. Because saying that monogamy is a social construct or pact doesn't mean it's bad, outdated, or less valid. The problem arises when we don't choose. When we simply go on autopilot.
You meet someone, you fall in love, you "close" the relationship, you move in together, you adopt a dog, you get married, you have children, and, if all goes well, you eat partridges. It's a sequence that seems to come standard.
What I mean by all this is that monogamy often happens out of inertia, and we don't stop to think if it's what we really want. For convenience, out of ignorance, out of fear, or due to cultural inheritance. When we have "the conversation" in a relationship, it shouldn't just be about whether we are a couple or not, but about how we are or want to be. And perhaps with some people you'll want monogamy and with others you won't, listen to that, choose. Because we all have the right to choose how we want to love.