Khyrial and the King by Marc Secchia

She is a winged warrior of the heavens. He is a doomed Elven King.

Khyrial the Zyrane Stormrider, disgraced Ayraelar warrior, has one mission – to keep King Vaylar alive. Her honour and return to her home above the Boreal Tempest depend upon success, for her dead father swore an oath she must keep at all costs
‘Evil knows how to bide its time. It is slow, as the turning of our worlds, and its memory is very long indeed.’
Powerful enemies plot a deadly end the Elven King’s reign. His fated attraction to the exotic bodyguard must be expunged at once. Khyrial will give her own wings to keep Vaylar alive. An elite warrior from birth, she is formidable, fierce and fearless, yet as the stakes rise, so do her forbidden feelings for the handsome Elven royal.
Vaylar is the King of Shalaemi, his sap rooted in the magical Elven forests, besieged by destructive Wyrms. His duty is to his realm. Khyrial is his sworn servant, an aerial huntress of storm and lightning. To a warrior of the heavenly realms, dishonour means death.
Catapulted into the lost realm of the Dragons, Khyrial and the King must make a terrible choice. One choice that will change everything.
Elf and Ayraelar. Man and woman. Never predictable, the storms of romance.