Star-Crossed Captive: A Sci-Fi Romance - J E McDonald

Sworn enemies from birth, one of them heals, the other kills.
In a future where our solar system's resources are scarce and the struggle for power never-ending, Nia, a trauma surgeon from the ruling class of the CORE, finds herself on the front lines against the ruthless Tellusians. When her deep-space medical station is attacked, she's taken hostage by Mace, a warrior who knows nothing but battle. Determined to escape CORE territory, he plunges her into Tellusian-controlled space.
Far from home, Nia's survival begins with uncovering the truth behind the lies she's been fed. But her growing attraction to the man who took her captive is an obstacle she never expected, his need to protect her a distraction she can't afford. As she navigates the complexities of a culture far removed from her own, her captor may turn out to be her only ally.
And when the Tellusian station comes under siege, trusting the enemy might be impossible while their opposing loyalties threaten to tear them apart.