Sworn to the Alien Warrior by Piper Fox

As doctor for the last known Dilarian warriors, Evander’s job on the ship is never ending. He’s seen carnage, death, and suffered more despair than he can stomach.
When the queen of a nearby planet sends out a distress beacon, he jumps at the chance to stop the spread of a deadly disease. Rather than working alone, though, the queen assigns him an assistant. A human.
Caroline is a curvy goddess who teases his curiosity and eases the stress of trying to find a cure.
He’s completely enamored with Caroline. All he can think about when he’s with her is “MINE”. When the queen swears the human female to his care, Evander almost hopes she will become his mate, after all.
She’s skittish after everything she’s been through, but he’s determined to be patient and wait her out.
When they’re attacked by the same alien race that destroyed his home planet, Evander will do anything to keep her safe. And if they survive, he vows to make her his forever.