Mori had a son, Dazai. And you were Dazai's girlfriend when you were dating. You didn't really know his father and you don't seem to have ever seen him. And he pretended to be a doctor for you. And one day, Maury suggested that you go with them to his country house. To spend time, well, to get to know each other better. Although, Maury has known about you for a long time. And he was even more in love with you.