The female protagonist's family adopted the male protagonist. What was the theme of this book?

-------------------------------------------------------------------------------- [Title: The male protagonist was adopted by the female protagonist's family when he was young…] The male protagonist grew up in an orphanage. Later, the female protagonist's father adopted him. The male protagonist vowed to live a good life from now on. He saw that the female protagonist was the heart of the adoptive person, so he deliberately tried to please the female protagonist and tried to be a good brother. The female protagonist liked the male protagonist very much. When they grew up, they secretly dated. However, the male protagonist never wanted the female protagonist's father to know about their relationship. He insisted on calling each other brother and sister, which made the female protagonist very sad. Later, the female protagonist sneaked into the Pub one day and met the lead singer of a band (male supporting role). When he was young, he stayed in the same orphanage as the male protagonist. He mentioned to the female protagonist the wishes of the male protagonist when he was young and said that the male protagonist had always been used to listing his plans one by one before implementing them. The female protagonist found the CD that the male protagonist had saved. Only then did she know that the male protagonist's kindness to her was actually premeditated. The female protagonist said that she had changed her mind and wanted to break off the marriage on the eve of the male protagonist's proposal to her. The male protagonist was stunned and simply left the female protagonist's home. From then on, they would never contact each other again. A few years later, the female protagonist's father fell ill and the company was on the verge of bankruptcy. The female protagonist returned to the company to help, but because it was not her line of work, she was mentally and physically exhausted. One time, the female protagonist ran into the male protagonist when she was running around for funds. The male protagonist was already a famous investment expert at that time. He earned whatever he invested in. The male protagonist gave the female protagonist some advice, but the female protagonist completely did not believe it based on her last impression of the male protagonist. Later, the only financial assistance that the female protagonist could find was from the male protagonist. She even ran to the male protagonist and refused. In the end, the male protagonist seemed to return to the female protagonist's father's company to take charge. At the same time, he also invested a large amount of money. Only then did the company slowly stabilize. Everyone who knew the male protagonist laughed at him for spending a sky-high price to get back his old love. Only the stupid female protagonist thought that the male protagonist was coveting her father's company again (even the female protagonist's sick father knew that he was not). Finally, of course, it was Happy Ending. The female protagonist gradually accepted the man her father wanted to marry back then (the female protagonist's father only wanted to remarry after losing his wife for many years, not having an affair...^_^). Excuse me, does anyone know this book?