If your Wife was in a coma, would it really be that bad to have zex with her from time to time? After all you are the one taking care of her financial wise and bodily wise. Giving her baths, changing her diaper, putting pourage in her feeding tube.
Some sort of will would probably help though. I guess it could be a man as well if the wife crushed up viagra or oysters in his feeding tube.
People have needs. If it does not hurt the coma victim, whys not?