Her leaving the room an enemy but then somehow winding up unconscious. No physical signs of being "dealt with" or knocked out.
Sounds like a classic case of Fictional Split Personality Disorder.
Perhaps Tofu, the author/artist, is pulling a page from Villainess Isekai and she is, at her core, evil, but her new reincarnation personality is screwing with her morality.
Maybe even a little bit of Xenogears character(s) Fei, and counterpart, ID.