A story of master and slave reversal.
The heroine is a mystic, and she is a daughter surnamed Wang from a vassal kingdom in troubled times. The male protagonist was born as a lowly slave, became a commoner by the grace of the female protagonist, and later became a prince in troubled times, the overlord of three parts of the world.
For the sake of the heroine, the hero went to jail on her behalf in a foreign country, and the two agreed to get married after they were released from prison. A few years later, the heroine returned to her own country to get married to avoid disaster.
When the country was destroyed, the male protagonist's cavalry broke through the city gate and imprisoned the country's leader. She was also captured.