Dear my lady

In a far off country, in times of war and turmoil, a young soldier of the crown named Fran is sent off to protect two sisters, a strategist named Anne-Maria and a witch named Lorena. As she is fully under Anne's service in protecting her, she is "my lady" while Lorena, who fights with her, is "Lady Lorena" to her. When Fran's romance with Lorena is discovered, they are separated and Fran and Anne are taken to the capital. But that won't stop two young women from writing letters to each other. Yet, they can't let anyone find out that it's them communicating, so every letter starts with "dear my lady..."