Covert Mission by Lynn Shannon

Duty is all he knows.
Logan Keller spent his military career saving lives, but none of that prepared him for raising his out-of-control teenage niece. He’s desperate to get through to her. A charity designed for teens seems like the answer, but when Logan arrives to speak to the director, he interrupts an attack on the woman’s life.
Danger surrounds her.
Willow Cassidy has dedicated her life to helping teens in crisis. When she’s assaulted in the parking lot of her charity, Willow fears the lime-light created by her uncle’s state senate run is to blame. And the threat isn’t over. A second attack proves someone is determined to kill her.
A tenuous plan.
Logan can’t leave Willow unprotected. Pretending to be her boyfriend is easy—keeping his growing attraction hidden is much harder. Every move designed to keep her safe ramps up the threat against her. Will Logan’s covert mission save Willow’s life or will it be a deadly failure?