Negative experience: A married couple who were living six hours apart opened up their marriage. When I met them they were not having any obvious issues with the arrangement. Eventually it came out that the husband was lying about partners both to his wife and to the other women. The rules of their relationship allowed him to have sex with other women as long as his wife knew about them, and yet he seemed compelled to lie whenever possible. The wife gains some comfort from the support of her lover, and has not yet decided whether to end the marriage.
Does this have anything to do with polyamory. It sounds like a lack of emotional maturity (I predict that he would have been cheating, regardless of the openness of the marriage.)
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.