The punishment for premarital relations is marriage without the possibility of parole–oh, I mean, divorce. Poetic justice. This is also true of one who rapes a woman who is not already betrothed (raping a betrothed woman is adultery and incurs the death penalty for the man). Some people object to this because the rape victim is “forced” to marry the rapist, but that is not exactly true. The woman’s father can judge whether or not its in her best interest to be married to that rapist or to stay under his protection.
I think if today a rapist were charged with the lifelong responsibility to pay every expense ever incurred by the victim, provide food, clothing, and relations to her, and no matter what abuse he suffers never be able to rid himself of the debt and duty she incurs, his rapes would be few and far between. Hell hath no fury like a woman scorned. He may do it once. He is unlikely to ever do it again. In fact, he’s unlikely to survive. To my mind, this is better than a few years in prison being cared for by the state (including the victim!) and then the opportunity to do it again with similar light consequences. In the Torah, there is no free lunch for rapists. She will suffer for life whether she marries him or not; the marriage ensures that he will suffer for the rest of his life to whatever degree her heart desires.