Sifrei Mitzvot para sa Exodo 22:15

One who seduces a virgin maiden is fined fifty sela'im pure silver and this is a fine. And if he raped her the same penalty would be levied. This fine is a positive commandment from the Torah, as it says "the man who lay with her shall pay the girl’s father fifty [shekels of] silver":

What is considered seduction and what is considered rape? Seduction is an encounter she desired. Rape is when he has relations with her against her will. Any woman who has relations in the field is presumed to have been raped and we treat such a case as a rape case until witnesses testify that she had relations of her own volition. And any woman who has relations in the city is presumed to have been seduced since she did not cry out in distress, unless witnesses testify that she was raped, for example if a man drew his sword and said "if you scream I will kill you."

The seduced woman who doesn't want to marry her seducer, or if her father did not want her to wed him, or if the seducer didn't want to enter [into marriage]- the seducer pays the [fifty sela'im] penalty and goes on his way and we don't force him to marry her. However if he does want to marry her, he doesn't pay a fine rather he writes her a ketubah like one would for any virgin maiden. However regarding the woman who was raped, if she or her father don't want her to marry her rapist they can decline collect the [fifty sela'im] penalty and go on their way. If she and her father want her to marry her rapist but the rapist doesn't want to marry her, we force him to marry her and he has to pay the penalty, as it states: "she shall be his wife" and this is a positive commandment. Even if she is lame, blind, or has leprosy he is forced to marry her and he cannot divorce her forever, as it is stated: "he shall never have the right to divorce her." This is a negative commandment.