Please explain why does prostatitis last so long?

Because...: Prostatitis has been one of most misused daignosis, and its context has evolved and changed over time especially over the past two decades, resulting in coining a new term, chronic pelvic painful syndrome/disorder. The DX of bacterial prostatitis is made on positive bacterial culture from post-prostate massage prostate fluid and urine. So, most cases are mistreated. For detail, see doc timely.