Why does Paul Morel come back to his mother in the end?

Mrs. Morel's illness is a major reason for Paul's return, but in the end, we have to remember he's never left her. Paul's mother is at the root of all of his decisions, her approval serves to determine his actions. Her investment in their relationship is stronger than any of the women he's been involved with, and her death frees him to do what he's always wanted to do.... to travel and get out in the world. In the novel's conclusion, we see that Paul is now free.... hopefully free in movement and free to love.