I recommend "Fickle President, Don't Pester", a modern aristocratic novel, to you. The plot matches the information provided. In order to save her family, the female protagonist married into a wealthy family. After that, she was told that the groom had not returned for a night. It turned out that the person who had sex with her was actually her husband's elder brother, and it was also the "poor" ex-boyfriend she was forced to break up with. The male protagonist regarded her as a treasure in his heart. Even if he fought with his brother for her love, he would not show mercy. The plot is fictional, please do not imitate it. I hope you like this fairy's recommendation. Muah ~😗