Hallowed Ground [Flight & Glory Series, Book 4] - Rebecca Yarros

Josh Walker is loyal, reckless, and every girl’s dream. But he only has eyes for December Howard, the girl he has yearned for since his high school hockey days. Together they have survived grief, the military, distance, and time as they’ve fought for stolen weekends between his post at Ft. Rucker and her schooling at Vanderbilt. Now that Josh is a medevac pilot and Ember is headed toward graduation, they’re moving on - and in - together.