Edman, from what I get from you. Your wife is very selfish. What I think you should is simple. She can either start making an effort to give you some attention(bj, handjob) or forget any attention to her. It isn't right, is she truly has a sex drive and yet won't let you finish after she cums. She is not living up to her marriage vows. If anything next time she wants to be done and doesn't want you to finish. If possible masturbate and cum all over her face.

Hellboy, you could say that you have a slightly different situation in that for some reason your partners sexdrive has dropped and yours hasn't. There are multiple reason for this and some we don't even see right away.
Depression, stress, lack of sleep and pain are just a few that come to mind. So maybe see his doctor for in over all physical would shed some light on it.