E, Just read through your sitch. So sorry you are on this crazy boat. Yea i too can draw some parallels on my sitch, when reading yours.
If you guys are at point where you can suggest books to each other: Suggest him to read this "Hold on to your NUTS". One thing i realized ASAP after my W filed was that my emotional immaturity played a big role. Years of being told that i was doing mistakes made it even more worse and killed my self-esteem. Reading the NUTs book really helps you realize your role as a MAN in the relationship. Reading through your sitch it seems like your H really did not know what he wanted or how to get it in mature manner, right from the beginning. So him reading this book should help him. I know it did for me.
The way you explained your sitch was in a calm mature manner. That tells me your are quite level headed I dunno, one reason you stayed with him this long even when signs were visible...were you trying to save him from himself? or it could have been co-dependency.
Either way...Him going away and coming back this many times is crazy. He also knows that you will take him back. Your 180's could be a tightening in that area.
Also, his positive attitude regarding reading the books or at-least agreeing to the MC even though he does not believe in them says that too likes to have an R with you but has no clue how. This was exactly my situation. I kept telling my W that i needed help to figure out how to be happy with her. In your case it could be that your H thinks that if he runs away that the problems will go away. If this the case, he's gonna come down to earth real fast.
Hang in there.
BITS M 38 W 36 D 7 Married 15 yrs W left for 6 months in 2009 W Filed for D 01/03/11 piecing now...