Pay The Piper by Mary Brock Jones

Secrets are revealed; questions must be answered, as two lovers caught in a maelstrom of opposing loyalties face their toughest fights yet.

For five years, the Terrans ruled Hathe, taking whatever they needed, especially the energy-rich mineral, urgonium, Earth must have to survive. For five years, the Hathians kept their world safe by hiding behind a façade, posing as subservient peasants and pretending all the wealth and knowledge of Hathe had vanished. Then came the time for Hathe to fight back, and for the Terrans to learn how wrong they were.

Now the war is over.

Hamon Radcliff was Head of Security for the Terran forces; his wife, Marthe an Castre, belonged to the Hathian resistance. Surviving the peace was always going to be tough for lovers caught on opposite sides. Both have done what they must to protect their home worlds and those actions have consequences. Nor does the end of war take away all the bitter anger between Hathe and Earth. When that anger finds an outlet, and turns its glare on Marthe and Hamon, peace time becomes downright dangerous.