What is the narrator referring to "the boss" and "the boy" rather than giving name of these characters in "The Fly"?

In Katherine Mansfield's short story "The Fly," most of the characters, including "the boy" and "the boss," are mostly referred to not by their given names but by nouns which indicate their position or their relationship to another character. "The boss" is the narrator's friend and at first is defined mostly by his position of authority in the company he works for. "The boy" is the boss's son. There are also "the girls," referring to the narrator's daughters, and "the wife," referring to the narrator's wife.
The story focuses upon the boss's difficulty in processing, or coming to terms with, the death of his son. He seems numb and is unable to cry for his son. There is a distance between his son and himself that he can not cover, or perhaps an emotional detachment, grown wider over time, that he is unable to reconcile himself to. Referring to his son simply as "the boy," rather than by his given name emphasizes this sense of detachment.
The fact that "the boss" is known only as "the boss," rather than by his given name, suggests perhaps that he has lost what identity he once had. One inference is that, since his son's death, he has defined himself more and more according to his job as a way of distracting himself from the pain of his son's death. It is perhaps easier to accept a death if one is, for example, "the boss" rather than the father.