Why does Adam send his daughter and son to live with Aunt Cordelia in the novel, Up a Road Slowly?

Adam is so devastated by the death of their mother that he cannot bear to raise the two younger children. A university professor, Adam provides the educational and socialization experiences for his children, but he is not available for them emotionally. Julie comes to regard him as a "holiday parent," because he is in her life for only good times and special occasions.