Write something like this and you are bound to attract a wide range of opinions. Good for you. Controversy is great for a writer’s bank balance. Morality is subjective. There is no ideal way to navigate intimate relationships that works for everyone. We all have to find our own way.
Monogamy suits me, but it’s not for everyone. If we were all honest, kind, and self-aware, respectful of all others and free of emotional baggage, almost any arrangement would have a high chance of long-term success. Unfortunately, we’re human and doomed to screw up at some level some time. If you can find what makes you happy, and make someone else happy in the process, that’s the sweet spot. Good luck to all. It isn’t easy.