Mother embraced by her daughter's boyfriend

My husband only comes home on weekends... Chiaki's mother, despite her husband's belief in her daughter Ryoko, is recommended to divorce her and is unable to say anything. One day, Ryoko brings her lover to the house. Chiaki didn't have a very good impression of Takeru, a part-time worker whom he met at his part-time job. When I told Ryoko about this, he was refuted. However, Chiaki should have seriously stopped Ryoko and Takeru's relationship at this time. A few days later, the tragedy happened...