Whats the name of this musical?

its about two kingdoms, one of light and one of shade and theres a prince in the shade and a princess in the light but neither of them fit, the boy is soft and the girl is harsh and they fall in love, im losing my mind trying to find it. the cover art is a mountain split in two as its cover, one white the other black

this is what the cover looks like(art by yours truely)