I think might be a bug but I can't find violet anymore i maxed her relationship in one fight I lost her and can't find her any more in the well
It is usually found either near a well or in inventory (as an item of clothing). Or at someone's place, for example, at Domenea's.
I completed demon so I can't find her in her place anymore I didn't see her in a item for clothes and there is only one well right?
After defeating the general, Celica receives a special artifact. After that, the location remains empty. Anything else can be found in other places or in the story.