the play is based on a myth called Pygmalion, it's named after the myth, because the idea was that he turned Eliza into the woman she became, but the original story is about a Greek man who makes a statue. and in the play (which was the original, not the movie) Henry Higgins didn't fall in love with Eliza, he didn't even think he fell for her, they "romanced it" for the sake of promoting a terrible moral in the film. In the play, he bullied, threatened, and emotionally abused her, but she realizes her worth, and left