Monogamy is a pair bonding strategy as old as humans. It developed at roughly the same time as polyamorous strategies. There’s a strong body of evidence that it became a very prominent strategy around 10-20k years ago, especially in areas with resource strains.

If you want to have multiple partners, by all means, do so, but don’t pretend it’s some construct. It’s a sexual selection strategy hardwired into many different species, including humans.

It just happens to coexist with polyamorous strategies in our species.