Let her go. She has made it clear that this is more important than the relationship to her (or at least it sounds that way from your perspective). If you are not able to give her the freedom to explore what she wants, and she is unwilling to forego these activities, then you are at an impasse. If there is no grey area, no room for bargaining on either side, then you don't have any choice than to be gracious and let her go.
In an evolving V with:
VioletLight, 40, Bi Fem. Hinge.
Katla, 45, (unsure) Fem.
My musical obsessions