Red Leopard (The Vistaria Affair Series) (Volume 1)

If they give in to their desires a whole country will fall.

Calli Munro, soon-to-be-economics-professor, arrives in Vistaria during La Fiesta de la Luna, a combination of Mardi Gras and Carnival, and is arrested for violently resisting the amorous advances of strangers. She's sprung from jail by a commanding civilian the Loyalist military refer to only as leopardo rojo. Calli is inexplicably drawn to him.

When Calli formally meets Nicolás Escobedo, the bastard half-brother of Vistaria's president, she realizes she is in trouble for it is the mysterious leopardo rojo. Their attraction is powerful and mutual, despite everything they do to deny its existence.

Vistaria totters on the very brink of revolution and anarchy. It needs only a tiny nudge to tumble the country into the abyss of bloody war. Then the insurrectos learn that the President's brother is having an affair with a hated Americano... 
____

Red Leopard is Book 1 of The Vistaria Affair series.
Book 1: Red Leopard
Book 2: Black Heart