I know the ML is in love with her and won't kill her.
But she really feels like someone with Stockholm Syndrome. It's not like overnight he turned into a good/kind person, he's only nice to her NOW. Dude gave her what's equivalent to PCP, forced to her play in a murder game (even if that's written like some rite passage). I don't think a normal person should just "forget" that.
Although manhwa logic it's fine, since he treats her well, even if everyone is faceless ants.
I'm also glad there's no tragic backstory/justification of his cray-cray actions.