In Chapter 3, the narrator squirms in secondhand awkwardness while Mrs. Van Hopper makes a fool of herself in front of Maxim. By the end of the scene, Maxim uses verbal irony and dramatic irony to establish rapport with the narrator at Mrs. Van Hopper's expense:
He got up at once, pushing back his chair. “Don’t let me keep you,” he said. “Fashions change so quickly nowadays they may even have altered by the time you get upstairs.”
The sting did not touch her, she accepted it as a pleasantry.
After droning on at length about subjects the narrator cannot believe Maxim would want to hear, Mrs. Van Hopper has been summoned for a dress fitting. Maxim uses polite-sounding language as he excuses her. He makes it sound as though he recognizes the importance of the dress fitting and respects Mrs. Van Hopper enough not to keep her from urgent matters. Under the mask of politeness, though, there is another interpretation. The "sting," as the narrator calls it, is the idea that Mrs. Van Hopper doesn't seem to do anything quickly. Her long-winded ramblings have wasted everyone's time, and at this rate she is never going to make it upstairs before the fashion cycle turns over.
Maxim's verbal irony is also an attempt to create dramatic irony. Mrs. Van Hopper does not notice the insult hidden behind politeness, but the narrator does. Maxim later sends the narrator a note apologizing for his rudeness. While he may say he is sorry, he is also making clear that he meant for her to catch the fact that he was making fun of Mrs. Van Hopper. More even than making light of the older woman's clueless nature, Maxim wants the narrator to be in on the joke with him. The dramatic irony draws the narrator to Maxim by appealing to her sense of self-importance.