Well this is a problem I have never seen before....

Try this first: take him to CAS. Save him to your library. Now go to your library and put your recently saved sim of him into the same CAS that he is. Delete the old him. Put the new him back into the game and try to make a relationship with the wife. Let me know if it works.

edit: You may have to revert to an earlier version of the game to try this, if you already deleted him.