The Prince 'loves' her because her personality did a 180 and the engagement isn't called off, as
@Chrana said. Problem is, both personalities are opposite extremes, one being a high-handed, snobby and judgmental bully and the other being a quiet little sweet thing everyone can fall in love with. They're very clearly not the same person, as a traumatic 5 minutes and quick death, events so sudden that she wondered if it was all a dream, isn't going to rewrite your character settings. It just rankles me all wrong when a 'villainess' decides to become a better person and therefore IS, right at that moment, the embodiment of purity and wholesomeness. This is your protagonist, is a slight internal struggle, something to give your character a growth too much to ask for?