It would also help to find out what is inhibiting him, and to get him to increase his libido. It could just be that there is something about sex that he is not entirely comfortable about, such as some form of performance anxiety. If nothing like that is holding him back, then maybe he can try supplements like L-arginine and ginseng. Definitely a multivitamin. I don't know. It just seems healthier to me to try to resolve things by moving in the other direction.