Avalon Tower (Fey Spy Academy) by C.N. Crawford, Alex Rivers

Avalon Spy Academy rules: spy on the fey, resist falling for your mentor, and try not to die in the process.
As a bookseller, Nia saved up for years for her dream vacation—drinking champagne on a beach with her favorite books. But her dream turns into a nightmare when she's kidnapped by a muscular, tattooed jerk of a fey named Raphael.

Yes, kidnapped.

It turns out Nia has a magic power, and Raphael demands that she train at Camelot's elite academy for spies. Raphael is hellbent on revenge against an evil Fey king, certain that Nia's powers can help. But Nia is in way over her head--asthmatic and out of shape. She’ll be lucky to get out of there alive.

Still, there's no escape when Raphael is watching her every move. He's lethal, dangerous, and hot as hell. When they're sent on a dangerous missions together, he becomes harder to resist. Touching him is playing with fire. Is she ready to get burned?

If you liked Frost and City of Thorns, you will love Avalon Tower.