Yes, sometimes you do have to ride the horse you have, play the hand you are deal, ....and all those other over-used sayings that tried to teach common sense.
Unfortunately, from what I have observed, "common sense" is no longer that "common." Settling for less than a perfect relationship, is also no longer acceptable. Our grandparents and great grandparents probably viewed a successful marriage as one where you didn't starve to death, your spouse didn't beat you (or abandon you) and where your kids survived into adulthood, with anything else being "frosting on the cake."
Part of what I find interesting in reading many of the comments and posts is the degree to which people are "torn between leaving their spouse or can't wait to end their marriage."
Especially, in the SSM forum, (if I were to generalize) I see people who are wanting to try to save their marriage more. (Although MWD has made a career of trying to help people save marriages, so those on this forum are a self-selecting minority of the troubled marriages out there and most are trying to save their marriage, which is why they ended up here.) Also since it takes time for a couple to work themselves "into an SSM" I see more long term relationships with other reasons for staying together (shared retirement, children, home mortgages, relationships that are basically positive except for the sex, etc.) discussed on this forum. Since I am generally pro-marriage, I find the comments/posts more interesting and emotionally/mentally challenging.
Actually, I found the discussion in another thread (your thread) using the "economic theory of sunk costs" as applied to a SSM to be facinating. Your discussion with "Walking/Virginia" was something that I had to think deeply about. One of the things that I kept thinking about was if "deep, unconditional love" really was a kind of "sunk cost?" I know that I would give my life to protect my children and my wife, they mean that much to me. If donating an organ would help them live or survive, I would not hesitate no matter what the state of our relationship was.
I also know that I will "love" my wife till the day that I die for all she has done for me, for bringing and raising two wonderful children into this world, and for being my true love and compantion for about 40 years. While I could be so frustrated with her and hurt/damaged by her regarding an SSM, to the point that I would divorce her, I would still love her for all that we had together. Perhaps that is what unconditional love in an SSM may be about.
That is why I also respect those who have chosen to remain with their spouse even if there is a huge hole in their marriage relationship.
I hope you find happiness and what you are looking for.
>43 years of marriage--My wife and I are now closer than we have been in decades. I believe that my SSM is over.