I've read through all of the thread and I feel your pain. I entered into a triad with a couple ~ childhood girlfriend and her husband (vee). We lived together. It seemed like it ought to be perfect because she and I already loved each other, and it turned out that her husband and I had an immediate connection the quickly turned to love.
And that was when it hit the fan. Turned out, my friend was okay with the sex, but not the love that developed between her husband and I. (Kind of effed up, huh? I mean what could she possibly have been thinking?) Anyway, my role went to sexless secondary almost over night, with me trying to be patient while they worked things out. The indefiniteness of the waiting pretty much drove me batshit crazy. Yet, I kept hanging in there because of my connection to her husband. (I could certainly relate to your description of how you feel about your guy.) It came down to the fact that he couldn't believe that she could turn around 180 degrees from discussing "moonlight marriages" to "it sickens me when you touch her". He kept thinking that given her initial enthusiasm, he could turn it back around. I was pretty sure he wouldn't be able to, and yet, I wanted to believe. It went on less than a year, but it seemed an eternity.
I no longer live with them, although miraculously we have all remained friends, and still love one another. I am moving on my life, yet he and I are still deeply in love and miss one another terribly. Like you though, I know he would miss his wife terribly if he were to leave her. Additionally, they have children and I knew from day one the children would be paramount in any decisions.
My point in sharing this is that I know how you feel, and secondly to recommend that if at all possible you try to get that timeline defined. Limbo is complete hell.