Dragon’s Vow by JD Monroe

A loyal dragon prince.
Long ago, Prince Zayir Moltenheart made a solemn promise to his twin sister, the queen of the Ironflight dragons.
I will do whatever you ask for the good of our family.
He just didn’t expect to make good on his promise by marrying a shapeshifter princess he’d never met. With war on the horizon and enemies closer to home, Zayir sacrifices his freedom to secure a future for his people.
A dutiful princess with a secret agenda.
As the daughter of a powerful shapeshifter clan, Ohrena al-Katiri has long expected a marriage of convenience for political gain, not love. But marrying the playboy prince of the Ironflight dragons proves to be a surprise and a challenge that takes her far from everything familiar.
A wedding of convenience.
Zayir is pleasantly surprised to learn that his new wife is as intelligent and thoughtful as she is beautiful. But overhearing nasty gossip on their wedding night leads him to pull away from her, sending their new partnership down a rocky path. As they navigate a diplomatic dance, they soon learn that they have misjudged one another.
Polite affection quickly ignites into something powerful and passionate. But when the prince discovers his new wife has been keeping dangerous secrets from him, he must decide whether he can trust her with the safety of his people. Will love bloom, or will their differences be too much to overcome?