Alien Vows by Carmen Webster Buxton
Yulayan Bellaire has grown up knowing she’s different. Her mother is human but her father is Wakanrean. No matter how Wakanrean she looks, no matter how much she tries to blend into Wakanrean society, her human half is still there. Still, Yulayan expects to mate as all Wakanreans mate, totally by chance, as soon as she comes near a man with compatible pheromones. And then one day she meets Kamuhi Hailoaka, a physicist from Terra who finds her unique genetic combination appealing, and she discovers that her human half is more in control than she had thought possible.