Answer:
The narrator emphasized the phrase "by her casual whim" because it shows how Judy could let Dexter do anything for her.
So, this shows what will happen to Dexter's future that Judy could just let him do what she wanted, especially that Judy asked him to attend the dinner the following day.
Explanation:
The question above is related to the story entitled "Winter Dreams," which was written by F. Scott Fitzgerald.
Before mentioning the phrase "by her casual whim," Judy and Dexter met again. This time, Judy asked Dexter whether he could drive the motorboat so she could surf while being driven behind it. As Judy demanded him to go faster, Dexter obediently did as he was told. This shows how Dexter fell for Judy and that he could just ask him whatever she wanted.
