Dark Horse by Melissa Pearl

He can’t let go of the past.
And it might cost him a future with the woman he loves.
Nate knows how to solve crimes. He’s dedicated his entire life to the force, sacrificing everything in his desperate attempt to absolve himself of the guilt he feels over his own mother’s unsolved death.
Sally loves Nate, but three years of waiting for him has proven one thing: his career will always come first. Not her.
Frustrated by his constant absence, Sally does the unthinkable. She walks away.
Devastated by the break-up, Nate throws himself into a Jane Doe case. But he soon discovers that solving yet another crime does nothing to fill the hole inside him. To make matters worse, Sally is moving on and he doesn’t know if he can ever win her back.
But he has to try…especially when unforeseen circumstances put Sally’s life in danger.
Especially because he might be the only one who can save her.

You’ll love Dark Horse, because of its heart-wrenching romance, nail-biting tension and twists you won’t see coming.