Royal Mate by Juniper Hart

Poet knows too much. Max is sent to kill her, but is also the only person who can save her. A heart-pounding romance that tests all loyalties.
Poet has always had an interest in ancient civilizations and thinks that she might have solid proof that dragons exist. As a woman of science, she has the drive to be the first one to prove the existence of these mythical beings. When she realizes her research is threatening her safety, it could be too late. When a mysterious man rescues her, she is taken by his strength, masculinity, and the way he brings out her primal instincts. Even though she feels like she can trust him, she also senses he is hiding something…

Max is sent to kill Poet, who is threatening to expose the dragons from Misty Woods. When he meets Poet, he can’t tame the flames of passion that burn within his heart. Besides, there’s just one more problem: she’s a princess. The repercussions of killing such a high-profile woman could be catastrophic.
Max’s loyalty to his family is put to the ultimate test. If he doesn’t kill Poet, his family will turn away from him. If he doesn’t save her, he will never forgive himself.