The childish conversation between Rob, Dick, and Barry shows three immature middle-aged men who have not yet escaped adolescents. Instead of being married with kids and enjoying the brief time they have left on earth, they argue because Barry, feeling left out and lonely, is jealous of Dick having a date with a girl instead of going out for a drink with the guys. Because they are unable to stop arguing about girlfriends and scum bagging ones friends, conversations which teenagers or young guys in their twenties have and not thirty year old men, they have reached "adolescence and just stopped dead" (151).
Being caught up in that type of conversation reveals a lot about Rob.
His mind, like his record collection, is frozen in time because, even though he is thirty-five, his mind "drew up the map and left the boundaries exactly as they were" (151) and that's why his relationship with Laura is failing.
His immature conversations are a direct reflection on himself, a poor depressed ex-DJ whose girlfriend dumped him because he cannot choose what he really wants to do with his "life" and therefore he's trapped inside his music, adolescent mind, and record shop looking out critiquing everyone except himself.