Hiro Syndrome

When a guy in anime, usually a well-loved or attributed character, goes after a girl who doesn't want him, whose rejection makes him act like a total asshole. Usually applies to gay men in Boys' Love anime who act all hetero over one specific girl, much to fans' dismay; however, it can also apply to canonically heterosexual males or males in non-BL anime when fitting the criteria of NICE GUY TURNED RETARDED THANKS TO BITCH. Often used as a plot device in fan fiction.

"Wow, did Steve totally just ditch his best friend Michael for Mikayla or what?"

"He's only acting like a jerk because of Hiro Syndrome."