Her Dragon by Fiona Davenport

Artemis Drake had good reason to be grumpy. The dragon shifter was older than all of his pack mates, but he still hadn’t found his fated mate. Not until he hunted down the little thief who stole a precious rock from his cave and discovered she was destined to be his.
Marielle Beck thought she’d made a discovery that would impress her geology professor. But the lunar meteorite she found during a hike turned out to belong to someone already. The sexiest man she’d ever met…who insisted they belonged together.