Quoting bumbling: he wants to stay with me he feels there is no passion or desire in our M he is unhappy
I am having a really hard time believing that I am not the sole cause of this unhappiness. Nothing I have done (DB for 2 1/2m) has helped him feel anything for me.
What are the kind of things you picture the two of you doing in happier times? What kind of recreation do you both like? Hobbies? Ways in which you enjoy spending time together? Why not do one of those things one evening this week. The best direction to take with someone "sitting on the fence" is to start building some good times together. Work at getting the good times outnumber the not so good. However, if he's not in the mood / declines, then pleasantly let him know its OK if he doesn't want to join you, and spend the evening doing something you enjoy and for that evening take a break from focusing on R.
When you come back and he sees you had a good time, next time you ask he may consider taking you up on it. Its all about creating a new cycle of what works. It happens a little at a time, but eventually you get there and when you do he will discover those feelings are back.