Dolores's third psychotherapist at Gracewood (she scares the other two away), Dr. Shaw helps her achieve some major breakthroughs: She loses weight, ditches her homophobia, confronts her anger at her mother and father, and starts to see herself as something other than an eternal victim.
Dr. Shaw pretends to be her mother, enabling Dolores to say, "I love you, too, Mommy" (18.52), and achieve some closure on that tumultuous relationship. He becomes a surrogate mother for Dolores, taking her back to the womb, i.e. a swimming pool, and guiding her through the coming-of-age process all over again. In other words, Dr. Shaw gives Dolores a do-over on her childhood.
One thing he can't break Dolores of at this point, though, is her petulant attitude. She quits therapy, even though she's not ready to be on her own and despite his insistence she stay. But she has grown enough to at least acknowledge the good the man has done: "Dr. Shaw was the first parent who hadn't left me" (18.1), she says, which is definitely a mark of some progress on Dolores's part.