Face Of The Enemy by Sandra Barret

Helena 'Dray' Draybeck is a cocky military brat, and Jordan Bowers is the daughter of a high ranking ambassador. Both want to be top pilots when they finish fighter pilot training at a Terran military space station. Both live under the shadow of very different family legacies. Just when it looks like smooth sailing for their success as cadets and their growing attraction to each other, the Novans declare war. Dray and Jordan now have to survive an acceleration to active duty and a dangerous secret that threatens their happiness together. They learn that the enemy has many faces.