Sterling by Kathi S. Barton

Marty liked her life just fine. She was alone in the world, and waiting on tables would get her by until she finished college, but the girl she was training wasn’t working out. And the girl got her fired—now what was she supposed to do? She needed that job to survive.
Sterling Calhoun’s encounter with the she-devil was over, but the nightmares still lingered. The only thing that helped him deal with the nightmarish pain were his paintings. And through is Grandda he met Marty, his mate, but Sterling hadn’t been himself for a very long time….

Marty knew a few shifters, so she knew what it meant when Sterling told her she was his mate. Oh, hell no, this guy had to be nuts, the “mates” she knew were a strange lot, and she didn’t want any part of it….