My Cruel Salvation by J. Kenner

He’ll keep her safe, no matter the price.
Investigative reporter Ellie Holmes has uncovered billionaire Devlin Saint’s dark and dangerous secrets, and he has both stripped away her protective armor and tamed the wildness within her. Bound by a shared past and the hope of a blissful future, they grow even closer, each exposing more of themselves as their love deepens.

But now that Devlin’s true identity has been publicly revealed, old enemies appear, intent on destroying Devlin. And while he vows to enlist all of his resources to protect her, Ellie soon realizes that the only way to save them both is to take the last, final step to fully join Devlin in the dark.