Shadow Target by Lindsay McKenna

Fate was not finished with U.S. Marine Corps Captain Shep Porter and Willow Chamberlin, his ex-wife, a former Air Force Combat Jet Fighter pilot.

Shep works undercover with Delos, a global charity organization, and his upcoming assignment is to reinforce the charity’s many schools in northern Ethiopia, a dangerous region known for international terrorists who hunt, kidnap girls and women and sell them into the European sex trade.
No one is more shocked than Shep when the Delos mission team tells him Willow is the pilot-in-command. Can he get along with his ex-wife and focus on the many civilian schools that need security upgrades? After all, it was his issues that had forced Willow out the door.
Now? As his heart blossoms with hope for a second chance, he wonders if he dares to tell her the truth that he still loves her. Does she still care for him? Unbeknownst to them, a cutthroat terrorist organization is stalking Willow in earnest. Will love be enough to save her?