Thief by Grace Brennan

Lily Abrams spent the last few years since her husband’s death suffocating under a cloud of grief. She’s finally putting herself back together, but there’s one more thing she needs to do before she’s ready to step into the future. Her late husband’s best friend disappeared after the funeral, and she needs to find him and make sure he’s okay. But when she sees him again, she’s immediately suspicious. Something isn’t right about his new life—and she’s not leaving until she figures it out and knows he isn’t in danger.
Noah Benson has felt like a piece of himself was missing for as long as he can remember, but he was holding it together until one of his best friends died. Now he’s spiraling, but he’s determined to fight, throwing himself into his job as an Enforcer with everything he has. Then, Lily shows up out of nowhere, full of stubbornness and suspicion, and she’s digging into his life, determined to find answers to questions she shouldn’t be asking.
Noah hasn’t seen her in three years, but there’s a reason for that—the attraction he felt for her, that he never should have had to begin with. When Lily volunteers to go with him on a mission, he has to make sure she never finds out the truth—that he’s a shifter, and that he’d always wanted her—and he has to protect her with his life. Because if he loses her, he knows he’ll continue spiraling right into oblivion.