What is the ruling on a relationship that has lasted for more than ten years between a man and his female relative, involving daily, secret, and frequent calls at late hours, and personal transportation, all while concealed from both spouses and acquaintances, with the man claiming it is merely a service-based relationship and that there is no fault in it?

A man's repeated contact and seclusion with a woman in a car is forbidden, and it is a pretext for falling into illicit acts. His claim that Allah knows he is doing what is right is a grave sin and a statement about Allah without knowledge. This is one of the greatest sins, as mentioned in Surat Al-A'raf (7:33). Speaking about Allah without knowledge is more forbidden than polytheism. This is what those who indulge in forbidden desires do, trying to legitimize their abominations. This person must repent and sever his relationship with the woman. He must be advised and threatened with the exposure of his affair to the woman's husband and relatives. If he does not respond, those trustworthy among their relatives can be informed to stop them.