Return of the Lycan King: Nicholas and Kristen by Candace Blackburn.
Nicholas is a Lycan who has been looking for his mate from his first thought of one. Nicholas is the owner and head of genetics research institute which investigates common human conditions and offers money for humans to donate blood for testing. Kristen happened to be of the humans that showed up to give blood in exchange for money. Nicholas knew as soon as she walked in that she was his mate but that she was still human, her Lycan physiology hadn't assert its self yet. But it would only be a short time before it did.
Kristen has a troubled past and it has changed her to be cautions when dealing with something that might have her fall back to her additions. But her pull to Nicholas is strong and they try to work through the changes that are coming
I enjoyed this book and hope the next book will be out soon.