If you take a religious teleological argument, the built-in sandwich of dopamine for pleasure and oxytocin for bonding after orgasm does serve to increase love in a relationship, which could be an argument for a natural monogamy. But it’s a bit of a just-so story there too

Much of evolutionary talk can sometimes fall into the teleogical; the language of natural selection often talks in terms of “Nature wants” or “nature’s plan” – which is a substitute for “God wants”, “God’s plan” – but otherwise interchangeable.