Imma just chuck an opposition view in here - I don’t believe monogamy is the right state for human beings. The idea you can somehow pick one person (usually when you are young) and stick with that person for 70 years or so seems absurd. I say that as someone whose parents and grandparents did exactly that.

The chances of you picking a single individual who meets your social, psychological, sexual and intellectual needs for 70 years is pretty slim. I think people settle.