If he is willing to save the relationship, get him to a doctor and have his testosterone level checked. It is not uncommon for a man to have that problem, and sure will affect his libido if it is low. Also, could he be suffering from erectile disfunction? If so, he may be embarrassed or fear that he can't perform. Is he on any kind of bloodpressure lowering medication? That can affect the latter, certainly. If that is the problem, as the doctor for a sample of Viagra. All he may need is to rebuild his confidence.

Dr.DougR,EIATS