These feelings were brought on by the thoughts he read, by the ideas he filled his head with, by a woman who’s head was equally filled with the same thoughts…and looking for someone to pour them into.
He is questioning his own philosophy.
The writer of these thoughts (he now questions) has no relation to his readers, he writes and walks away, while we suffer to understand it’s meaning.
The characters within the book are free as soon as you shut it’s pages, but the character you’ve become in reading them are stuck with you, in your psyche.
Thinking about these authors, he recalls Albert Camus “A Happy Death”, in that story there is a character named Marie. Like the Old Man Perez character from Camus “The Stranger”, Marie is a love interest of the main figure but like all characters which push for purpose (in this case in love/monogamy) she is disregarded entirely.
The person in this song finds himself trapped in an existential design by his partner, suffering the same treatment as those characters opposite the main characters in these existentially driven novels: “No Exit”, “The Stranger”, and “A Happy Death”.
He feels not for the center of interest in those novels but for the characters swept aside to further the point of a purposeless existence.