You asked for stories of endurance, so I will share a bit of mine.
JaneQ
Jane, thank you so much. Stories like yours, and others above, are exactly what I started this thread for. The only real exposure I had to Poly for a long time just seemed like a complete lack of commitment, not like what I really think something with the word "love" in its name should be like. In the BDSM community we were a part of for a few years (socially and exhibitionally, not in a swinging sense), poly seemed to mean something like one lesbian in the role of slave to a couple while also dating a straight man. It made no sense, and it never seemed to last more than a year or three.
My wife was so relieved to see in your post that putting the spouse above all others is a thing people do in this community. She's been really reluctant to use the term "poly" because what we knew of it really didn't seem to fit us. We still may not use the term for ourselves, but it's good to know that in ambiguity of terminology, people find their own stability.
turtleHeart: Thanks. I'm still working my way through Opening Up, but this is on my list now. It sounds like a worthwhile read for me.