Lessons With The Mothman by Kathryn Moon (Monster Smash Agency #3)

Elias - freelance consultant to Monster Smash Agency, and prestigiously rare moth fae - has never been in love. Granted, he's never been interested in the emotion, but with his friends mating with their clients, the new curiosity is keeping him up at night. If only the act of loving made any logical sense. And if only he could find someone to draw him in like the moth to the flame.

Victoria is looking for facts not feelings. She wants to understand why the monster species are so much more satisfied than humans, than her. But the handsome mothman who volunteers to aid her study wants to stimulate more than her intelligence. She's willing to explore their physical chemistry, but she wants no part of his designs on her heart.

Some lessons can't be taught, and love is certainly one of them.