Fans are left wondering why Justin Bieber has unfollowed his longtime mentor and close friend Usher on Instagram, with some speculating it could be due to a "big" reason.

Almost two decades on, Justin appears to have quietly cut ties with his former mentor Usher, 46, so we look back on their close 17-year friendship. Usher didn’t discover Justin but he was there early on in the Yummy singer’s career, having been brought on board immediately by Scooter.

The first theory about the Usher shade is dark. Some fans are drawing lines between Bieber’s unfollow spree and the ongoing Sean “Diddy” Combs saga. If you’ve missed it, Diddy is currently facing some pretty serious allegations including accusations of sex trafficking and racketeering.