Holden wants to preserve her innocent way of thinking because he sees the best parts of Jane in Phoebe. To him, Phoebe is the last true bastion of hope and sanity in a world gone sour. Phoebe is the only female that Holden is not afraid of, since the real world has not tainted her feminine innocence yet. Holden believes that he causes problems with all of the "pure" women that he has ever known, whether it is his mother or Jane, and he knows that he can fix all of that with Phoebe. She is the only girl that he is able to fully attach himself to without having to deal with romance. Holden can love Phoebe, and Phoebe can love Holden, but it can still be entirely innocent
Holden wants to preserve her innocent way of thinking because he sees the best parts of Jane in Phoebe. To him, Phoebe is the last true bastion of hope and sanity in a world gone sour. Phoebe is the only female that Holden is not afraid of, since the real world has not tainted her feminine innocence yet. Holden believes that he causes problems with all of the "pure" women that he has ever known, whether it is his mother or Jane, and he knows that he can fix all of that with Phoebe. She is the only girl that he is able to fully attach himself to without having to deal with romance. Holden can love Phoebe, and Phoebe can love Holden, but it can still be entirely innocent