The Heir by Kiera Cass (Book 4:The Selection series)

Twenty years after her parents' love story, Eadlyn, the future queen of Illéa, is preparing to rule. To ease political unrest in the kingdom, her parents suggest she hold a Selection—a televised competition for her hand in marriage—just like the one that brought them together.

Eadlyn is reluctant. She doesn’t believe she needs a partner and agrees to the Selection only to appease the public. But as 35 young men enter the palace to win her heart, Eadlyn begins to realize that love might not be as impossible—or unnecessary—as she once believed.