Doctor Du Maurier is not exactly certain how she arrived at this moment. Her mistake was believing that the boundaries she'd established for herself were complete, concrete and inscrutable. It was very simple: do not get romantically involved with patients; do not have sex with patients. Those boundaries remained uncrossed. Technically.
Perhaps there should have been one more tenet: do not let patients touch you. Comforting a client during a session with a hand on the arm was one thing—allowing one to wash her hair was… quite another.
Bedelia never expected to reach this level of intimacy with the devil.