A Man Must Marry Permanently A Virgin Whom He Has Intercourse With (Deuteronomy 22:28-29)
‘ If a man find a young woman who is a of marriageable age, who is not betrothed, and lay hold on her, and lie with her, and they are found, then the man who lay with her shall give to the young woman's father fifty shekels of silver, and she shall be his wife, because he has humbled her. He may not put her away all his days.'
Compare here Exodus 22:16-17. Where a young unmarried woman was of marriageable age and could therefore be presumed to be a virgin (she was a bethulah) and a man forced on her sexual intercourse, (the impression given is of undue pressure, although no doubt it would apply anyway), then the man must pay compensation to her family of fifty shekels of silver which in Exodus 22:16 is described as a dowry, and must marry her permanently with no right of divorce. It should be noted that this was both to protect the good name of her family, and to see to the young woman's interests. The penalty was against the man. The woman would not be bound to marry him if she did not wish to do so in which case he would still have to pay the compensation (Exodus 22:17). But society was such in those days that it was usually to her benefit to marry him.
It may seem strange to some that a woman should ever be married to the man who raped her. But we must understand the meaning of ‘lay hold of her and lay with her'. He may have been someone the woman knew well and was not necessarily averse to. His very action (in a society where everyone knew everyone else) demonstrated his deep feelings for her. There may therefore have been a willingness and readiness on her part. Indeed she may have encouraged it. Love did not necessarily play much part in the beginnings of most marriages in those days, and a young woman was expected to follow the directions and desires of her parents, even to the most unsuitable of suitors. Thus the young woman in these verses may actually have been luckier than most in marrying a man who really loved her. He would not necessarily brutalise her. And women did not then have the same expectations as today nor the same sense of their ‘rights'. They were trained to be submissive. Thus the prospect might not have appalled them as it appals us today. And there was always the opt out.
This example is a reminder to us that when a man and woman have intercourse God looks on it as putting them in a married state. They have been joined together as one flesh (compare 1 Corinthian Deuteronomy 6:16). They are one. Any subsequent sex with anyone else is therefore adultery.