Quote 13
So the days, the last days, blow about in memory, hazy, autumnal, all alike as leaves: until a day unlike any other I've lived (12.5).
The narrator's memories of his last few days with Holly fade into an indefinite picture because he's so sad at the thought of her leaving. He knows she's going to become a part of his past, not a part of his future.
Quote 14
[I] was moving out of the brownstone because it was haunted (19.1).
The narrator can't escape memories of Holly once she has left, and he can't bear to stay in the apartment since it's a constant reminder of her. He has to remove himself from the physical location of his memories in order to move on.
Quote 15
She was forever on her way out […] (8.2).
This short passage perfectly sums up Holly's life. She's always on the move, always onto something better.