What is the ruling of Islamic law regarding a man who suffers from a disease in his reproductive system that has affected his psychological state, and his doctor advised him to engage in sexual activity before marriage to regain his self-confidence, but he refused because he is a Muslim?

It is not permissible to commit indecencies before or after marriage, for there is no cure in them. Ibn Mas'ud said, "Allah has not placed your cure in that which He has forbidden to you." The man should frequently supplicate, remember Allah, and obey Him, and consult trustworthy doctors or the psychological counseling department to receive the correct guidance.