First of all my heart goes out to you, that is a painful story. I wish my W would take that kind of interest in trying to improve things! IMO, sex is a red herring in this situation and you have the equivalent of a walkaway spouse. You may want to post your sitch on the newcomers board instead as I feel you need more general DB help than just SSM.
WRT your BF, the "in love" feeling that he's referring to is a chemical reaction in the brain that lasts from several months to several years. It's predictable and normal that it will end. At that point a different kind of longer term love takes over which is more of a choice and takes work. That work requires incentive.
In your BF's case, he has either found OM, naively expected "in love" to last forever and is now confused, or something fundamental is broken in your relationship and his needs aren't being met.
What he is telling you is "script" and you should mainly ignore it. If you haven't yet, read "The Divorce Remedy". In my experience on this board, when you get ILYBINILWY, there is OW involved and your BF is confused. May not be anything beyond a temptation at this point, but something to be aware of. Men rarely jump without somewhere to land.
Read DR and try Newcomers.
Good luck!
Accuray
Married 18, Together 20, Now Divorced M: 48, W: 50, D: 18, S: 16, D: 12 Bomb Dropped (EA, D): 7/13/11 Start Reconcile: 8/15/11 Bomb Dropped (EA, D): 5/1/2014 (Divorced) In a New Relationship: 3/2015