I recommend Young Master Gu's Substitute Wife. It's a modern romance novel about wealthy families. The male protagonist's surname was Gu, and the female protagonist's surname was An. In the storyline, there was a younger sister marrying her older sister in place. From the beginning, the male protagonist was distant and indifferent to the female protagonist. Later, he was gradually attracted by the female protagonist's strength and kindness, and began a sweet journey. I hope you like this fairy's recommendation. Muah ~😗