Guard Her Heart - (Crown of Promise) by Hannah Currie

Book Synopsis

To all bar a few, the Guardian of Raedonleith is a mystery. To Lady Mykah, second daughter of King Lior, it's her calling. For the past four years, the mask has given Mykah a way to care for her people in her father's stead while she hides from them how distant their king has become. Never once has she questioned her mission nor thought the cost too high-until the night an arrow finds her. Though she has the courage of a knight and the calling of the Almighty, Mykah admits she would have died if not for the man who carried her to safety. A man who is as determined to keep his identity hidden as she is.

Six years ago, Sir Finnian lost his heart to a mysterious young archer. Though he searched, he never learned her name-until the night he shot her. On his brother's orders. Wracked with guilt, Finnian makes protecting Lady Mykah his new mission, never guessing how difficult it will prove to be. The Guardian has more enemies than she knows, and they're closer than she realizes.

The longer Finnian stays, the clearer the price of his vow becomes. Because the only way to win Mykah's heart will be to break his own. And the only way to keep hers beating will be to break it altogether.