I have a soft spot for this kind of gothic romance, so this worked for me. It sits in that older Dracula / Crimson Peak lane, where the horror is not only the monster, but the way love, duty, bloodline, and secrecy start closing in on the same person.
I also liked how the mystery is handled. The story gives enough signals early on to make the reader uneasy, but not so much that the tension disappears. There is a nice pull between what Raina knows, what she is avoiding, and what the people around her still do not understand.
The impossible part feels personal rather than just supernatural. It is tied to love, succession, and identity, so the ending has a tragic touch without needing to become overly complicated. Overall, I enjoyed this.