Storms of Allegiance by Melanie Cellier

Even absorbed in her studies, Delphine can’t forget Nik or his mission to find Grey. When he reappears with a plan to defeat Grey, she’s desperate to convince Amara and Hayes to agree—even if it means putting herself in danger.
But there are things Delphine doesn’t know about her own ability, and once in Grey’s orbit, it might not be as easy to extricate herself as she expects. Confused, and with her allegiance wavering, Delphine clings to the one certainty in the fog surrounding her—Nik.
But when the two of them end up stranded and facing a threat that could upend the entire kingdom, Delphine isn’t sure if she can rely on the man who’s stolen her heart. If she wants them both to survive, she’ll have to discover the limits of both her power and her will.

If you enjoy strong heroines, fantasy worlds, adventure, and clean romance, then try A Mage’s Apprentice, set in the same world as the completed Mage’s Influence series.