Hello, the novel you're looking for is "Pure Daily Life: Fujin Don't Fight for the Throne". The female protagonist of this novel found out that she had become Lord Fourth's wife during the process of transmigrating, and Lord Fourth was also reborn. In the novel, the female protagonist did not know that Lord Fourth was reborn at first, but she gradually discovered this secret as she interacted with Lord Fourth. After her rebirth, the heroine used her wisdom and experience to adapt to modern society while not forgetting to protect her status and family in ancient times. There are many interesting plots and characters in the novel. I hope you will like them.