Fae Reckoning. Royals of Embermere, #5

Defeat the queen and reclaim the realm-or all is lost forever. Despite beating the queen at her own wicked game and completing the Fae Heir Trials, the tyrant refuses to hand over the crown. Instead, she claims she'll rule forever. Using corrupt blood magic, she's made herself immortal. As true mates, Elowyn and Rush are supposed to be in this fight together. But the queen has stolen Rush's memory.
When she needs him most, Elowyn can no longer rely on the warrior drake who'd do anything to protect her. With the queen in pursuit, Elowyn has no choice but to run, abandoning him to the queen's evil clutches. Any hope for the salvation of their world falls squarely on Elowyn's shoulders. She is the true heir to the royal throne, daughter of the rightful queen. She's been chosen by the dragons themselves for a grand destiny.
Her friends have come to see her as their realm's only hope. But Elowyn's destiny has been hidden from her all her life, and now she must master the magic she should have learned as a child when there's no one to teach her. If she doesn't, her mate bond will be destroyed, and the friends and dragons she's sworn to save will all die. The Mirror World itself will fall to eternal darkness. The queen has made a single, fatal mistake, however.
She believes she's already won. While Elowyn wasn't learning to use her magic, she was learning how to fight-and how to win. The Fae Heir Trials might have ended, but the battle for the Mirror World has only just begun.