(Devarim 22:29) "Then the man who lies with her": "the man," and not the minor.
"who lies": any lying, (natural or unnatural).
"to the father of the na'arah" (and not to the father of the bogereth).
"fifty silver": Tyrian silver.
"and to him shall she be as a wife": We are hereby taught that he must "quaff his bitter cup" — even if she be lame or blind or covered with boils. If there were in her a thing of zimah (obscenity) or if she were not fit to marry into Israel, I might think that he were permitted to keep her as a wife; it is, therefore, written "and to him shall she be as a wife" — (connoting) a woman who is (halachically) fit for him (as a wife).
"because he afflicted her": to include an orphaned girl (as receiving the fine). From here they ruled: An orphaned girl who was widowed or divorced, the ravisher is liable (for the penalty); the enticer is exempt.
"he shall not be able to send her away all of his days": but she may be released from the levirate bond.