Talking with my GF, M, I think I have, with her help, begun to articulate a common, or easy enough, pitfall within the open relationship paradigm. (I am super rambly right now; sorry!)
How do you know when you should keep working with your partner on challenging things? When do you simply say: we are just two very different people, and our differences are not compatible?
It seems like open relationships could allow two (or more) people, who might find themselves incompatible within the confines of a monogamous relationship pretty quickly, to spend an agonizing amount of time trying to mesh their ever-widening differences.
I know J and I have gone through conversations (and by conversations, I mean super-high-charged-crying-despondent-argument-like conversations) when we have been in a super low time (mostly last summer; thank goodness we moved through that) that center around this idea. Do we want the same things? Do we have enough in common that we can compromise around the differences?
I think it can become even more confusing when one or more people have an "ideal" relationship structure in mind, but aren't emotionally there yet. Working through personal stuff can take such a long time, and is probably never done (although hopefully gets easier). So then you are continuously living in a "less-than-ideal" relationship which feels stressful and yucky.
So, I think a potentially good solution to this is to begin re-framing your relationship. Given your present factors, does your relationship feel comfortable and happy and satisfying? How does your partner feel? Are any differences or challenges within your relationship worth a short-term struggle? (It is my personal belief that chronic challenges often create chronic stress, which will take its toll on everyone involved, and is not sustainable.) Relationships will always change; they are dynamic creatures, given the dynamic individuals involved. So even if you once held an "ideal" in your mind, stay present within your relationship and work with what you have. Your factors will change effortlessly, and you will be given the opportunities to work through things as you are ready for them. And as long as you are moving operating with happiness and love in mind, even when needing to work through icky stuff (because you will sometimes), your relationship will serve you and your partner(s). And if there comes a time when you simply can't bridge differences, I think it can be helpful (although probably easier said than done) to allow your relationship to simply transition into a form that allows everyone to live in peace and happiness, even if it causes short-term sadness.