Negative, first-hand: long-term cohabiting partner of a couple of years convinced me into polyamory. In spite of me explicitly vetoing my two best friends, the partner proceeded to implicitly bargain away this boundary while convincing Best Friend #1 I was totally cool with it. This blew up while Best Friend #1 and his long-term girlfriend were visiting us for Christmas. After fucking up our relationship, she proceeded to do the same with BF#1 and his girlfriend. She then moved onto BF#2, who she subsequently married under apparently monogamous terms. BF#1 and I don't talk all that much any more. BF#2 and I never talk any more.
The moral of this tale: careless, selfish people can deal exponentially more damage in a polyamorous environment. Also, don't break up with people over Christmas if you can reasonably help it.
Do you think this outcome would have been different if you had not agreed to a poly relationship?
Related article: Polyhacking
Although polyamory isn't one of the "official" topics of LW interest (human cognition, AI, probability, etc...), this is the only community I'm part of where I expect a sufficiently high number of members to have experience with it to give useful feedback.
If you go looking for advice or articles about polyamory on the internet, you mostly get stuff written by polyamorists that are happy with their decisions. Is this selection bias? Where are the people whose relationships (or social lives, out anything) got damaged or ruined by experimenting with Consensual Non-Monogamy?
I'm posting this hoping for feedback, negative AND positive, on experiences with polyamory. I considered putting this in an Open Thread, but it occurred to me that many other LW readers might be interested in whether polyamory has drawbacks they need to be aware of. If you have experience with CNM (including first-hand witnessing, which has the added bonus of not requiring you to out yourself if you don't want to), please comment with your overall impression and as much detail as you would like to include (I am also putting my experiences there rather than in this post). If you've seen multiple poly relationships, multiple comments would make tallying slightly easier. (ETA: I will also try to upvote people who feed me data, a la LW surveys) If there are sufficient comments, I will periodically go through them and post a rough ratio of good to bad experiences at the bottom of this article.