I'm having difficulties with understanding to what exactly その理由 refers to in this sentence - 「その理由も、やはり深く考えずに。」 To the girl's strange behaviour or to the fact that he thinks that not thinking to deeply about everything is for the best?
I'd say it refers to 人生の処世術.
If I'm reading it correctly it's something like: Juu thinks not thinking too deeply about things is the secret to life.
As might be expected Ju did not deeply consider the reasoning for such a conclusion.
I'm having difficulties with understanding to what exactly その理由 refers to in this sentence - 「その理由も、やはり深く考えずに。」 To the girl's strange behaviour or to the fact that he thinks that not thinking to deeply about everything is for the best?