My current boyfriend ended a relationship with his girlfriend of 4 years because he wanted to explore poly and she couldn't/wouldn't. They were good in most other respects, it really was the start of the poly idea that was the beginning of the end, and they both seem to think so...
But, I don't know. Do people ever blame monogamy as a concept when their relationship fails?
How do you separate out the concept from the people practicing it, or attempting to? I guess for them two you could say it was the poly concept to "blame" but really if you look closer, they had fundamentally different ideas about freedom, about obligation etc that probably would have manifested in some other way had he decided poly was something he didn't want.
I'm just thinking about it now... what would that even mean, blaming poly alone as some abstract concept? So, you try something new in your relationship, you love it or hate it, then essentially what happens next is actually all about communication, honesty etc. What else is there?
As far as I see it, relationships work when good people get together and commit to treating each other well. The details of how that's organized seem secondary, so I would imagine that blaming poly would also be a symptomatic thing.
Or, of course, life just goes on and relationships end