Forest of Dreams and Whispers by Katherine MacDonald

A mortal raised in the land of Faerie, Juliana Ardencourt doesn’t remember the curse being cast.

But the rest of Faerie does.
On Prince Hawthorn’s eighteenth birthday, at the first drop of his blood spilled, the kingdom will be plunged into a century-long slumber…
And the Unseelie King will reign.
As his personal guard, Juliana is sworn to serve the vain, arrogant prince only until the fateful day, but when the curse is unleashed, Juliana alone is the one that can save him.
Connected to Hawthorn through their dreams, Juliana soon finds her feelings shifting for the boy she once swore to hate…
And soon swears to sacrifice anything to save him.