Hiya all,
I just wanted to say how enlightening I find this thread. I've always sort of had the same questions as Q regarding poly relationships. Perhaps I'm a cynic because of my own self awareness (being a scorpio is great in the passion department, but not so hot in the sharing department!)
I've never been able to bring a third into a relationship I've been involved in (for the reasons stated above), but have been involved in *ahem* fun scenarios with more than one person... just no one was my boyfriend, per se.
It's really great to hear how the dynamic works for those of you involved in successful poly relationships. To some degree I'm envious because I can very well see how fun and fulfilling, to all, more than one partner can be, and as I myself have discovered the joys, but never able to share with someone I love.
To reiterate a quote from before, if it works, it works. Communication and honesty are clearly essential in a poly relationship, as in any, but perhaps more so here to avoid any of the potential human responses to sharing. I think it also essential to be aware and know your own limits. Many of us have said it wouldn't work for us because we don't like to share full time, so we don't partake in a poly relationship. And that works for us.
Kudos to all of the succesful relationships... poly and monogamous alike.