The loneliest narrator ever?: Teju Cole's Open City

The alienated narrator: Isn't Julius, in Teju Cole's novel, "Open City," among the loneliest people in fiction? It's odd, because he has a good job, he refers frequently to "my friend" (as if he's his only friend?) with whom he shares information about jazz and other arcane topics, at one point in the novel he has lunch in Central Park with some friends, he has an ex-girlfriend and has one strange but successful sexual encounter - and yet, and yet - I have the overwhelming feeling that he doesn't know anybody but himself, with his finely tuned sensibilities and acute observations. He's in one of the largest and busiest cities in the world, and he spends much of his free time (and most of the novel) walking about, encountering people from time to time but often just observing, witnessing, and he seems alone in the crowd. In a more dramatic novel, he would be a dangerous character, perhaps a terrorist or (thinking of Camus again) a killer, but Julius seems to be a peaceful, reasonable content young man. Yet what are we to make of him? He gets mugged - doesn't tell anyone. His beloved teacher/mentor dies - he doesn't call for weeks, doesn't follow up when he learns of the death. His ex-girlfriend tells him she's engaged. He has no reaction whatever. He's emotionally, psychologically numb. We meet all kids of characters in fiction - that in part is why we read fiction - but Julius is a character to whom we have no key, no clue. He's a blank: solitary, personable it seems, super smart - but we don't know what makes him the way he is. His loneliness is enigmatic, not necessarily emblematic.