The thing to keep in mind is that her grandfather has been trying to get her away from the royal family ever since that incident, as he knew unlike the first prince, the second prince would just see her as a pawn for his advancement, hence the makeup thing was meant to try to make her unappealing to him and other nobles, though her beauty was still well, high (somewhat of a guess, but his ultimate goal being that he wanted to get her as far away from the nobility and thus essentially being nothing more than a political tool makes this likely the reason), it doesn't come up until later, but lana is not the saintess, what she is however, is the descendant of a goddess, and her grandfather knows it (at least i think, kinda hazy on a few details), hence she has a insane level of healing ability (the ability seems to randomly appear so not everyone in the family had it), which would definitely be used if found out by the nobles, fyi lana doesn't know this either, her grandfather wanted to essentially give her a normal, happy life, which he saw as impossible as long as she was bound by her noble status, her grandfather had been trying to find a way to annul her engagement for a while, but as it was a royal order, he couldn't do so by normal means, he also had to make her want to be away from the family, she was too kind hearted and would have given up her own happiness for the family, so, he had to make her want to leave.
For what it's worth, he's been showing up from time to time, making sure lana doesn't see him, at her restaurant to check up on her and make sure she's doing well.
Sadly, it seems no matter what he does though, she's likely to end up with royalty, as both potential love interests for her are royals.
Sorry for the long reply, kinda needed to lay out a good deal of spoilers.
<3 <3 <3
