I think this one is tough. I know a few people that consensual non-monogamy has worked out well for (long term), but most of the people that I know who tried it out it hasn’t gone well. So I’m not against it in theory, but it comes with a lot of caveats. I don’t personally know anyone who began a monogamous relationship, transitioned to poly, and had it end well. I tend to think of this scenario as a sign of relationship trouble, or a cause of it. Maybe it’s not polyamory’s fault that so many people in relationship trouble are drawn to it.