As it suggests, the love interests of the protagonist have to be older than the protagonist. However, it is only used when the age difference is quite significant, and either the physical/mental aspects of this difference gets some screen time.
Gu Nianzhi had no idea how to get the aloof and handsome Major General to fall in love with her. His eyes were dark and serious. "...Seduce me. If you can do it, I’m yours." Gu Nianzhi: "!!!" Disclaimer: The following stories contains sexual assault, rape, nonconsensual acts, mentally abusive relationships, and violence towards women. Readers are advised to proceed with caution.