If he ever starts rubbing up against you or trying to swoop back in, politely refer him to the book (there’s audible if he likes that) and let him know its an important part of you getting yourself better and understanding people more and maybe if he reads it some day and put in the effort (theres exercises aha)…
We’ll see. (Probably not but telling him to surprise you and put it in his possession so he can’t pass it off to someone else (i get the sense he would be self-conscious of the idea of people noticing him with it…All these games we play, sigh