The Movement of Rings — Nadine C. Keels

Sequel to The Movement of Crowns.
What lies deeper than fear? The Mundayne empire has prospered under the rule of King Aud, a ruthless man of war. Naona, a spirited imperial servant who holds Aud's favor, enjoys pulling pranks on her peers around the king's estate. But the time for laughter spoils when the citizens of Munda begin to oppose the taxes that pay for Aud's wars.
After meeting the princess of Diachona, Naona must choose between remaining loyal to her king and becoming another nation's ally. With the rise of unrest in Munda, how can Naona's heart survive intact: intact enough, even, for a chance at love with a foreign man?
This book is inspirational historical fantasy: fictional history in a completely fictional world.