The Literal Commandment
If a man seduces a virgin who is not engaged, and lies with her, he must pay a dowry for her to be his wife. If her father absolutely refuses to give her to him, he shall pay money equal to the dowry for virgins. (Exodus 22:16-17)
The literal commandment is that a man who seduces a virgin should pay a dowry for her whether or not she becomes his wife.