I recommend "Enemies: Jealous Prince's Cute Pet Concubine" to you. This book fits the plot information you provided. The female lead and the second male lead went to the male lead's house as guests. The male lead fell in love with the female lead and asked the second male lead for his help. Moreover, this book also had elements of an otaku battle and business. It was very interesting. I hope you like my recommendation. Muah ~