I've been a happy polyamorist for more than ten years now, I'll happily debate on the topic. Polyamory, relationship anarchy, or simply sexually open relationships have their advantages and disadvantages, and so do monogamy. Monogamy never worked for me, but polyamory did.

There are no intrinsic issue with non-monogamist relationship structures. Monogamy is not better or worse, it will fit better some people, but it is not for everyone.

I never met any valid argument against polyamory - so if you have some, let's discuss.