What hints does the fortuneteller say? What relationship level are you with Nel?
I’m at 7.6, and it tells me to share more about myself with Nel. … How?
[edit] I updated the game and kept playing a while longer - I think I got unstuck, her relationship meter is finally moving upwards again and I managed to at least see the form change event.
On a sidenote, if you wear Violet through the portal that strips you naked the game gets a bit confused when you go back through to the normal world. I had normal clothes with purple sleeves, and violet reset to staying at the well.