I suggest that it is likely to be a combination of items 1 and 3. I say that from my own experience in a sexless marriage.
It woukd be nice if the anguish suffered as the HD spouse was a shared concern by the LD spouse. Unfortunately, it does not seem to be that way.
I realize that choice 3 probably rings the most true for myself...I've been through a divorce before and even though my ex and I remained good friends after the anger and the eventual apologies...it is not something that I really wish to go through again.
You might consider that your husband (as does my wife) simply values something different about a "relationship." It is the mere appearance that there is one and that are no obvious visible problems that exist within while allowing the LD spouse to pursue what he/she values (something other than sex).
The disconnect between levels of satisfaction is what is so frustrating.
The Captain
Last sex: 04/06/1997 Last attempt: 11/11/1997 W Issues "No Means No" Declaration: 11/11/1997 W chooses to terminate sex 05/1998 I gained 60, then lost 85 pounds. Start running again (marathons)