>What about the assumption that nonmonogamy is psychologically damaging? "Different people are different," Jenkins and Ichikawa wrote. Many nonmonogamous people report that they come to feel less jealousy over time; conversely, many monogamous people complain of experiencing sexual jealousy. In response to the charge that nonmonogamy is "unnatural," Jenkins and Ichikawa pointed out that virtually no species are sexually monogamous, even if they are socially monogamous or pair-bond for life. ("Not even swans.")
Some people seem to be having wonderful polyamorous relationships while other seems to suffer in terrible relationships where they insists on being polyamorous.
For me this seems unrelated to polyamory. It seems more to be the case that the people who are emotionally stable have good relationships and the people who are unstable struggle to form good relationships.
At the same time it seems that polyamory might be appealing to many who can't make "normal" relationships work. So my guess would be there are two distinct groups who are drawn to polyamory.
Highly emotionally intelligent people who communicate their needs and function well within relationships who wants more relationships and people who struggle with relationships who sees polyamory as the solution and monogamy as the reason for their previous problems in relationships.
The main case where this isn't true as much is when a relationship is otherwise good, but there are specific things that are missing -- there's not conflict, just things missing. For example, if one person in a couple enjoys BDSM and the other doesn't, adding someone that can fulfill that desire can be quite helpful.
There's always exceptions, of course, but that seems to be the way things generally work out.
In my experience the opposite is true people DO become more mature in the presence of others. In general people tend to take a breath and try not to lose face by becoming upset in most social contexts. Also a third party can mediate conflicts, couples therapy comes to mind. Sure that's not the same thing as romantic involvment, but I can imagine conflicts deescalating just by having a third person around who can see both sides or take side or point out that the arguing parties are both behaving as idiots.
I dunno. I've known quite a few poly people. Most of them are indeed, quite miserable, and in some way or another, I see them as being an abusive relationship, where one person is enthusiastic about being poly, and the other is kind of forced into it because they have low self-esteem, or otherwise feel trapped. It's sad. On the other hand, I do know of at least a couple of people who are in, as I see it, quite happy, healthy, and equitable arrangements.
In either case, I don't really judge these lifestyle choices. What I don't "approve" of is manipulation and lying (infidelity). And that happens. It happens in poly relationships (where the liar will hide behind their poly status as a way to get blanket permission to do whatever, and exclude the other partner from knowing, because it's uncomfortable). But the ones who are mature enough to not resort to abusive tactics, I say more power to them. How do I have the right to tell other people how to live their lives, if it makes them happy?
Myself, personally, I don't think I could ever be in a poly relationship. I have a hard enough time with mono relationships. I would hope that if we had a more open society that came to mass-acceptance of poly relationships as a legitimate thing, that poly people would also respect those of us who want to be monogamous, and our "boring" lifestyles. Or maybe those of us who may choose no relationships. Indeed, some of these poly friends of mine are quite scornful of the monos. We're backwards, and old fashioned, burdened with some horrible, medieval "patriarchal" lifestyle. And they assume we're all judging them. Whatever.
Implementing it seems like it would be very difficult.
The civilizational staying power of polyamory is nil: it will devolve into the chaos of inner city single parenting or the barrenness of San Francisco.