What is the ruling on a legitimate marriage between a young man and a young woman who had a sexual relationship before marriage? And is it obligatory to wait three months to complete the marriage after repentance?

If the relationship occurred during the engagement period and before the marriage contract, it is pure adultery, which is one of the gravest sins. The two who committed adultery must repent sincerely, abandon the sin, regret it, and resolve never to return to it. Their marriage is not permissible except after repentance and the expiration of the waiting period, which is one menstrual cycle.

However, if the legal marriage contract has been concluded, the relationship is permissible even if the wedding has not taken held or the dowry has not been paid, and it is not considered an illicit relationship.