Like other posters, I too find a significant pattern in O'Connor's stories, but for me the most obvious issue playing psychologically is the human insecurity and some type of miserable awkwardness that O'Connor so masterfully plays on with her characters. Asbury is very miserable and depressed about the way his situation turned out, but Asbury is prideful. It's as if he has failed in New York, but can't admit to himself, let alone his small-town mother, that he is not a successful artist.
So, why is Asbury so caught up in this idea that he is going to die? It's as if he is running away from his problems, or just stabbing at the "ignorance" his mother has. Of course, like some other of O'Connor's stories, the main character is really the naive, ignorant one. Further, Asbury is painfully immature; he reminds me of a junior high school adolescent who stays home "sick" because they can't properly cope with other underlying issues. Asbury knew all along that he really wasn't going to die-which explains his rejecting of any medical care and his knowing that Dr. Block's delivery was that he wasn't actually going to die before Block even told him. He wants to die and takes this fever as an opportunity perhaps, but the real issue is much further beneath the surface. I'm not sure what it is, but maybe it an avoidance of adulthood, perhaps he is bitter with his mother for not showing him reality beyond the dairy farm, and he knows he can't deal with it.