The Inadequate Heir by Danielle L. Jensen — book slip

Zarrah, a soldier raised as the heir to an empire, is driven by vengeance against the Veliant family for her mother's murder.

As the Endless War between Maridrina and Valcotta rages on, Zarrah is determined to destroy the Maridrinian forces and kill the Veliant prince leading them.

However, a chance encounter with a mysterious Maridrinian man challenges her beliefs, igniting a passionate connection that forces her to question her path of violence.

As identities are revealed, Zarrah must choose between a chance at peace or continuing the cycle of war.

Third in the Bridge Kingdom series.