Forembra

Keo is a poor girl from the planet Forembra. It's like Earth, except a few minor details.
Semmter, who you could call the prince of Forembra, is Keo's future husband. Keo is taken to the castle, where she will live for the rest of her life with Semmter. While she's there, she discovers a hidden door in the ballroom. She doesn't know where it leads, nor when it will disappear and reappear, but as she tries to find out, she falls in a tangled-up sort of love with Semmter's younger brother, Relt. As they fall deeper into the mystery of the forgotten door, the deeper they fall into a forbidden love.
Keo tries to keep both relationships, but when she gets lost in the forgotten door's maze which now seems to be forever sealed, she must question her sanity. Who she truly loves. And what she's willing to risk.