I have been feeling that grief over the same issue. My AH wasn't capable of being that steady, devoted, loyal, helpful, "soft place to fall" kind of husband and I grieve the loss of what never was, and all the years I spent chasing it.
I'm particularly in the depths of it lately. The good news is that now, untied from him, I have the opportunity to find it in another relationship, which I never did while I was still looking for it in him.
And in case the idea of looking for those qualities in a mate is futile (for all I know) and codependent, I know that I am there for myself in the ways I wanted him to be. It just takes some shoring up of my own strength.