Isn't better to keep him by her side? If she can't see him, the witch can do anything she wants to him.
Though it would be funny to see the princess get angry and kill the witch, because the witch ate up Nadricka.
Nadricka's character is practically communicating in semaphore with how many flags he's waving. I give a 95% chance of treachery or death in the near future.
By her internal monologue it seems like she also transmigrated into that body from somewhere else, and now she is thinking that her intervention in this world is what it's making stuff go haywire, like the princess changing her mentality.