Mother and Son - Grand Format

A teenage boy left home because he thought he was unhappy. Nobody knew where he went. His mother was looking for him all around, but she did not find him. To wait for her son's coming back, she never went out with friends, never ate out, and : never traveled away. She did not accept a great offer for relocating her home, or even changing her home phone number. She just stayed at home and waited for her son.
She waited and waited for years. One day, the son came back, missing his mother. However, the mother was not at home anymore...