'The Little Green Plum in His Heart' meets your requirements! It was a romantic youth novel written by the author, Little Bear Ruantang. The female protagonist, Ye Muxi, was one year younger than the male protagonist. They were childhood sweethearts. On the surface, they were enemies, but in fact, they were deeply in love with each other. If you like this kind of plot, you might as well give this novel a try. I believe you will like it.😋I hope you like this fairy's recommendation. Muah ~😗