Mangaka clearly showed that the skill worked just now, so if they make her somehow resist it or later on retcon it by making him somehow purge it, then this story is more useless (as they show any tension is purely artificial and no risk exists) than I already consider it after they introduce a reincarnated NTR character.
... And yet I have a hunch that it (the charm eye not being permanent for the elf and mc not having to kill her) is exactly how it will play out.