Firestone by Claire Cullen

Exiled for a terrible crime, Prince Daegan lives a solitary life until an injured omega washes up on his shore.
The unloved, unwanted son of the king, Prince Ellix dreams of the day he’ll finally make his escape through the marriage circuit. That day never comes. Instead, his father arranges a marriage for him. But when he reaches his new home, Ellix learns it’s all a lie. He’s not destined to be anyone’s husband, just a plaything to a powerful king. So he escapes.
Daegan’s quiet life is interrupted by the arrival of the mysterious Ellix. At first, he wants rid of the timid omega, but Ellix’s companionship grows on him. Ellix is certainly in no hurry to return to his life, and Daegan has nothing to return to. Drawn together by loneliness and longing, they finally see their chance at happiness. But as truths come to light—about the present, and the past—the outside world threatens to tear them apart.