| Quote #4
"Boy, that's rotten. And you meant to be her friend. What a bastard!" (15.4).
This reveals to us Joe Bell's definition of friendship. He is appalled that the narrator thinks Holly is really involved in the mess with Sally Tomato. For Joe, true friendship is the complete belief in a friend's innocence.
| Quote #5
"Well, I might be rotten to the core, Maude, but: testify against a friend I will not" (17.24).
So, Holly actually does think about someone other than herself. For her, friendship cannot exist without loyalty (even if we think her loyalty might be a little misguided in this case.
| Quote #6
But the address, if it ever existed, never was sent, which made me sad, there was so much I wanted to write her (19.1).
In the end, the narrator just misses his friend a great deal. He wants to share the accomplishments of his life with her, and he feels her absence in a very real way.