This essay is spot on! As I noted in another comment, my husband and I had a very good and we thought very progressive monogamous relationship. It was only when we opened up after 20+ happy years together that we discovered just how much we had unconsciously bought into beliefs and understandings of what marriage is that were created by other people, sometimes thousands of years ago. Having to communicate more (rather than relying on known structures) and having to really actively co-create our relationship was stupendous. It's something everyone should have the chance to do, even if they choose to continue to be monogamous.

You are speaking as someone who doesn't know what he doesn't know. I'm telling you, this is 100% on track in every respect.