There are books Harry’s been reading that he’s had Lissy charm to look like a Rune book far too simplistic for Hermione’s post-OWLs level, each of them dealing with the nature of a dominant-submissive relationship. It’s not uncommon in the magical world for one reason or another, including political marriages like his own, and while he doesn’t mind misbehaving for a good cause or when it’s over an important thing he has been trying to be good.