I recommend "Bamboo Horse Raising Chronicles". This book described the experiences of the male and female protagonists who were childhood sweethearts from elementary school to university. The male protagonist was three years younger than the female protagonist. The two families were neighbors. The male protagonist liked the female protagonist since he was young. The male protagonist's mother was very rich. There were also scenes where he used money to save the female protagonist's father. The writing style was dark, and the male lead had a sickly and delicate nature, which slowly attracted the female lead. I hope you like this fairy's recommendation. Muah ~😗