His Dragon Princess by Amelia Shaw

Veronica
My whole world crumbles when the sorcerer Anthony reveals to me that Iain is my Fated Mate. Having been raised as cousins, we are familiar and not in a good way! All my life he has belittled me, annoyed me, and ignored me. He’s exerted his authority over me at my expense and has never shown an ounce of regret for it.
I don’t know whether Anthony speaks the truth—my heart wants to believe his words are lies—but I refuse to remain and find out. And so, I flee to the mortal realm, where Iain is no longer my problem! Or at least, I thought so.

Iain
Enjoying the freedoms of my station, I take to the wing, enjoying a flight with my liege, King Damon. Together, we discover an old wreck we’re keen to investigate. But the joke’s on us when our joy ride quickly succumbs to disaster.
The ancient house collapses around us, trapping us both within the ruins and debris of ages past. It’s going to take a miracle for help to find us, and the king is gravely injured. Time is running out. I can only hope that the woman I’ve tormented and scorned all my life will put her pain aside to become our savior…