What is so frustrating right now is that the communication and conflict resolution skills we still need to improve in order to have a good co-parenting relationship are the same ones we'd need to have a happy marriage. I'm annoyed that I have to do that work (with H) anyway without the benefit of feeling like it was leading to a repaired marriage.
Claire, what if you re-framed this? These conflict resolution skills will benefit you in your co-parenting, and they'll benefit you in a new R. That R might be with your H and it might not be. So what? You get the benefit either way, yay for you.