I recommend the Imperial Pet Cold Concubine: The Emperor, Please Let Go to you. This novel was an ancient romance novel similar to Xi Mian's Lost. The male protagonist regretted it after falling in love with someone else. The male and female protagonists of this story were childhood sweethearts, but the female protagonist fell in love with someone else and rejected the engagement with the male protagonist, causing the male protagonist to eventually become the most cowardly prince in the world. A year later, the female lead was actually going to marry her lover! In order to be able to be with the female protagonist again, the male protagonist started a series of actions to save the female protagonist. I hope you like my recommendation, Mwah ~😗