What is the ruling of Islamic law regarding a man marrying a woman who is not a virgin, with his prior knowledge of that, especially if she is innocent of losing her virginity, and what is the fate of her relationship with that man in light of the aforementioned circumstances?

The questioner must sever the forbidden relationship with the man and repent to Allah. He, in turn, should propose to her if he is serious about marriage. The man must understand that virginity is not proof of chastity, and that the hymen can be lost due to reasons other than fornication. The man should fear Allah and not waste the woman's youth. He should marry her and protect her if she is truthful with him, and both of them must repent from their previous relationship.