Ancient Ties by Marie Johnston

Born to be Guardians…
Chayton Eagle comes from a strong line of wolf shifters, his father an ancient in their pack. Chayton proudly acts as a Guardian, defending the colonies from danger—both from outsiders and from threats inside the pack. The one thing he doesn’t need is a human-raised female on his team—especially not one who passes out each time she shifts! Never mind that she was trained by elite Guardians, Chayton doesn’t need the distraction of a tall, sexy-as-hell redhead when he’s working. He has to focus. And he has to remember he’s scheduled to take the blood oath with a female, a long-ago pairing arranged by her parents. It doesn’t matter he and Kaitlyn are fated mates.
She can’t be his. Not now. Not ever.

Destined to be Mates.
Kaitlyn Savoy knows Chayton is supposed to be her mate. Too bad he’s such an ass about her human upbringing making her weak. Too bad she’s been assigned as his partner to take down the feral shifters threatening one of the colonies. Too bad she’s so damn attracted to him. As the mission continues, Chayton is captured by the ferals, and Kaitlyn proves her worth as a Guardian. During the rescue, she uncovers the secrets of her past, secrets that will affect her future. Despite his best efforts, Chayton’s opinion of her begins to change, his respect growing—along with feelings he can’t deny. She’s become part of his life, part of his heart. A fact his soon-to-be inlaws notice—and they intend to put an end to the temptation Kaitlyn poses to Chayton.

No matter what.