...we are taught to put fun and serious pursuits on a continuum as opposed extremes, when this dichotomy is entirely false, made even worse when we act as though we can instantly exchange one for the other...Exerting yourself at a task that is serious and rewarding can still be quite fun, but doing something fun because you have a neurotic need to pack your life full of un is pretty much a guarantee that any long-term benefits you derive will be entirely happenstance.
It's a false premise to say that most monogamous people have chosen monogamy. Most people belong to the religion they were raised in...because that's what's familiar. That's the milieu they grew up in, and, for better or worse, they're just continuing the pattern. Until this traditionalist mindset is shaken loose, you would likely try from reflex to impose notions onto nonmonogamy that are not only untenable in the new context but spel sudden and messy doom even in situations that otherwise could be worked out.