What is the importance of nicknames in the short-story collection, This Is How You Lose Her?

When Yunior was younger he talked about one of the girlfriends he had at the time. He kept referring to her as "Whitegirl," which represents how little she meant to him since he didn’t even use a name for her. Yunior refers to his ex-fiancé simply as his fiancé or his ex. When he gets a student pregnant, he simply refers to her as the law student. Yunior frequently comes up with simple nicknames for the women who he dates because he doesn’t respect them, which is why he keeps cheating.