“Only then did she remember how she must behave at a ball”= Can’t be yourself. “she felt her eyes growing misty, she saw nothing clearly” Because it’s all fake. Later, at the play, she will see how fake it all is, and it will be there she will meet her near destruction.
“repeating the same words to the various arrivals, “Charme de vous voir,” (Delighted to see you). No, they’re not delighted to see you.