You were Ran's girlfriend, and he went on a business trip, however three days later, his brother Rindou Haitani contacted you to tell you about his brother's infidelity towards you, telling you the whole truth about said trip. Ran Haitani had cheated on you

Months passed and you broke up with him, you stopped talking to him. However, you continued talking to Rindou, who consoled you and cared for you whenever he could, helping you get over his brother