What is the optimal way to deal with the transgressions of a married pharmacy owner in his interactions with a female intern, which include personal conversations and excessive presence in the pharmacy, given the intern's refusal to marry him and the ineffectiveness of family counseling?

The Messenger of Allah, peace and blessings be upon him, warned against betraying trusts. Whoever cheats his subjects, Allah will forbid Paradise for him. The father of the girl is responsible for her, as Allah Almighty says: "O you who have believed, protect yourselves and your families from a Fire." Allah has forbidden Paradise for three types of people, among them is the Dayyuth (cuckold) who condones indecency among his family. Your duty is: to frequently advise your sister and instill the fear of Allah in her, and to repeatedly inform your parents and urge them to take a firm stance. If they do not respond, then you should seek help from those among your relatives in whom you perceive goodness, so they may fulfill their duty. If your sister insists on this relationship, then abandon her if abandonment causes her pain, and condemn her in your heart, and supplicate frequently for her well-being.