Ignis by Lula Monk

Captured. Auctioned off. Forced to make a decision between life or death.
Clea knows where she is, and she knows what she is expected to do. She just can’t bring herself to do it. When a handsome, aged creature named Ignis wins the bid for Clea’s body, she makes up her mind: she will fight her way out of his arms before she lets herself be forced into his bed.
Ignis didn’t want to be at the Hub, and he definitely didn’t want to be in the position he was in now: that of wooing his way between the legs of the human woman before him. What he really wanted was his wife, the one whose flame had been extinguished many annums before. But the fate of his entire planet rested upon his shoulders, and he was determined to do his duty.
And yet, the longer Ignis is around feisty human Clea, the more the ruler of the war planet Incenda realizes the Earth woman has her own fire deep inside.
Will Ignis persuade Clea to be his mate and help him save his home planet, or will the heat of their warring desire and hatred for each other consume them both?