Well, in "Jeremiah's Song", the narrator's flashbacks are sentimental/bittersweet, and he is remembering things such as before Ellie went to college. He remembers how he used to sleep with her and smell the cocoa butter on her skin.
It is bittersweet, as he misses being with her before she changed. This also applies to Macon, as the narrator describes here: "For a long time he was just another kid, even though he was older’n me, but then, all of a sudden, he growed something fierce
