I like how half the current comments are complaining about how a crowned prince got off scot-free. For an attempted rape of a commoner. In a middle-age setting.
Even if she were still a noble, it would hardly matter. As long as the family was compensated, normally monetarily, it was entirely a noble's rite. This case, a royal's rite.
Is it archaic? Yes
Should you be mad? Yes
Is the manga worse because of this? No