Wolf Promise by Asa Maria Bradley

He has good reasons to hate witches.

Wolf shifter bodyguard Bolt Varg wants nothing to do with magic, but loyalty to his alpha forces him to work with a new client who reeks of supernatural powers and hides scores of secrets. Bolt is supposed to protect her, but his body wants to do much more than just shield the beautiful woman with which he’s now stuck. Is the attraction real, or is she using dark powers to enchant him?
But she’s got him under her spell.
As the CEO of a Fortune 500 Fitness Company, Regina Lansford can’t afford even a hint of scandal. Someone is trying to kill her, so she hires a private security firm instead of going to the police. But the broody sexy bodyguard who’s her new fake fiancé awakens more than her hormones. She’s kept her abilities suppressed for a lifetime. Why does this stranger make those dangerous powers impossible to control?
Can they learn to fight deception and dark magic—together?
Caught in a high-stakes game where none of the opponents are what they seem, Bolt and Regina are running out of time. Will they learn to trust each other—and their sizzling attraction—before a savage killer claims their lives?