Answer:
Pygmalion's main flaw as a character in the play is his arrogance and belief that he can teach anyone to become a smart and polished person without taking into account the person's underlying qualities and sentiments. Due to this flaw, he treats Eliza, the young woman he tries to reform, like a mere object and disregards her feelings and preferences. In the end, Pygmalion realizes his errors and starts to respect and value Eliza as a person.