Unexpected Angel by N.J. Walters

Angelina Astoferus is on the run from her uncle, who wants to marry her off as part of a business deal. Her only hope is to find a spaceship to escape on—and a man willing to take her virginity, since her being pure is part of the deal. A desperate escape attempt leads her to the loading docks of the planet Oasis, where she spies Amos. Captivated by him, when the opportunity to sneak on board his ship arises, she takes it.

When Amos Marks discovers a stowaway on his ship, he knows she is big trouble. He and his brothers don’t need two dangerous enemies—her powerful uncle and the jilted warrior from Gravas—but Amos can’t turn his back on her. He decides to help her with her outlandish plan, but neither of them expects that the physical connection between them will lead to so much more.