Reckless Hearts by Em Petrova

He was her husband’s commander.
Now he’s her only protection.
And loving him may be the most dangerous mission of all.

Grant “Church” Upchurch has carried the loss of his teammate for years—and the one thing he never expected was to see that man’s widow take a job at the new Black Heart Military Training Facility. Seeing Zee Davis again stirs more than guilt and ghosts of the past—it awakens a protective instinct he can’t ignore. When a job throws them into a fake marriage, she’s suddenly at his side, in his space…and under his skin. Wanting her feels wrong. Letting it happen feels so right.
Zee came to Black Heart Ranch to rebuild her life and finally feel like herself again. But something has been following her from place to place—and when it finds her here, she can’t ignore it any longer. Church makes her feel safe in a way she hasn’t felt in years…but the way he looks at her, the heat in his touch, reminds her she’s still alive.
The line between friendship and desire blurs fast as they race to uncover who’s stalking Zee. They’ll have to face the danger closing in—and the attraction neither of them can outrun. And when the threat hits too close, they realize it’s not just their lives on the line—it’s their hearts.