Winter Dreams — Melissa Marr

A Wicked Lovely ebook prequel. The Summer King has spent eternity romancing women, stealing their mortality as he seeks his missing Summer Queen. When he met Donia, he knew that she would either break his heart or heal it. Then Donia failed the test to be his destined queen, and Keenan lost more than his missing sunlight. With the Winter Queen growing stronger every day and centuries of failure, Keenan is ready to quit trying. But if the Summer King doesn't save Summer, humanity will perish with it.