Court of Bone and Amethyst by Aurora Grey

The Court of Nightmares has been taken by the enemy and Sarielle and Zyren are on the run, in search of an army that can help them win the war ahead. They’re the only ones who can save Valaron, but Sarielle’s magic is out of control, Zyren is fighting inner demons, and neither of them can trust the other.
In order to make things right, they must work together, but that may prove to be the one thing neither can do. When they reach the Court of Memory in the far north, in hopes of making an alliance and winning back the throne, they find themselves entangled in even more danger and deception.
But the darkest secret is the one Sarielle is keeping from the man she loves…