Tinker, read about the stages of marriage. You will find that in many books, it is also in MWD's Divorce Remedy.
Unfortunately, many WAS use the excuse of ILYBNILWY to leave the M. Sometimes it may be that the expectations are not realistic, fueled by misconceptions on what it is, the stereotype Hollywood love. Also, many WAS meet an OP and feel all of those feelings that they once had for their spouse.
My H felt the same way and initially had felt hopeless about our M, feeling that he was stuck in misery.
In our case, Retrouvaille helpe him see that there are many kinds of love, and that one can make a decision to love to maintain the committment.
Perhaps you can discuss with your H about what mature love is? maybe you can watch the movie Fireproof? I don't know, if you are religious, or spiritual, but understanding what Biblical love is also helps.
Me:49 H:45 D:12 M:14 T:18 Bomb: 6/26/10 EA: 9/3/10, fizzled out slowly, now ??? 11/5/11 Retrouvaille Finally piecing.... Its peaceful at last, but we got a looong way to go