Morgath the Skullreaper by Cara Wylde

Audrey Griffin’s life has been a fifteen-year countdown to vengeance. To deliver the justice her slaughtered family was denied, she’ll offer herself as a tribute, a lamb walking into the lion’s den. Her mission: get into the bed of the one orc she holds responsible – Morgath the Skullreaper – and kill him in his sleep.
Morgath, a powerful mage forced into the role of captain, despises the human world he’s trapped in. For years, he forbade his warriors from taking human mates, but now his horde is turning on him. To prevent a rebellion, he must do the one thing he loathes: take a human bride to secure his position. He’ll trust the skull he wears to mask his distaste when he’s forced to look upon her.