The depression that follows when you finish a book and/or book series (possibly along with the movies) and realize there will be no more sequels and no matter what you do you will never have the same feeling of anticipation and exhilaration from reading the book series. The feeling that after all the waiting you know you will never get the feeling or feel the same ever again.
Symptoms include: crying, looking at fan pages obsessively, yelling harry potter spells, looking up harry potter facts out of desperation to find something you didn't already know, annual pilgrimages to The World of Harry Potter at Universal accompanied by more crying, dreaming of harry potter characters or dreaming your harry potter.
and the Deathly Hallows
: The scar had not pained Harry for 19 years. All was well.
Guy: Holy crap... it's all over
Guy 2: yep it's all over.. time for Potter's Syndrome to set in