According to Shaw, what have readers and audiences assumed about Eliza's future in Pygmalion?

The answer to this
question can be found in the rather lengthy afterward that the author provides us with at the
end of the play which describes the future of the main characters after the curtain falls. In
this afterward, Shaw seems to want to set the record straight about various misconceptions that
audiences and people have come up with regarding the fate of his heroine. Note what Shaw says
about the conclusions that people have reached after watching the play:

Nevertheless, people in all directions have assumed, for no other
reason than that she became the heroine of a romance, that she must have married the hero of it.
This is unbearable, not only because her little drama, if acted on such a thoughtless
assumption, must be spoiled, but because the true sequel is patent to anyone with a sense of
human nature in general, and of feminine instinct in particular.

Thus Shaw writes the afterward to this excellent play to combat the mistaken assumption
that Eliza, as the obvious and impressive heroine of this play, would marry Professor Higgins as
its hero. However, according to him, such a view clearly shows a mistaken understanding of her
character and the play as a whole, as if you understand the characters carefully, you would
never come to such a conclusion. Most amusingly, Shaw argues that Higgins would never marry
because the most important woman to him in his life is his mother, who could never be
replaced.