Cheers been looking for a walkthrough for days now. This oughta make it easier..I guess I don't have to ask, but just to be sure: Is her bar full?
Also, I remember being able to ask to have Violet back once "Mistress" has had her fun.
Maybe you just need to progress the story, because after this should be the Masquerades to progress further.
You can always check the walkthrough, if none of that helps:
https://f95zone.to/threads/town-of-magic-v0-66-011-deimus.64257/post-11410196