Welcome to HCM
We understand your concerns
You need to believe the doctor or doctors or find a doctor whom you can trust and ask his advice. From the description you gave, the problem seems to be psychological than physical. Doctor's will not bluff in these matters. They are telling the truth.
Is your friend afraid about his sexual life due to some hidden reasons? Find out. Take him to a psychologist
and know what psychology is behind this. Ican help you if you desire so.