A Bond so Fierce and Fragile (Compelling Fates Saga #3) by Sophia St. Germain:
 
Torture. Darkness. Loss. That’s what the Fae king has planned to break her. But Elessia is prepared to fight. She is ready to fight her way out of the king’s claws, fight to save Havlands from rebels and Fae alike, and above all, fight to return to the one she loves. But in the end, it’s her own life she might need to fight for the most, and even though her mate will do anything, including rip the entire world to shreds, to keep her safe, there is nowhere to hide when the gods themselves are after you.