Off Broadway’s nonprofit MCC Theater has abruptly ended its longtime relationship with award-winning writer-director Neil LaBute, canceling an upcoming production of his new play “Reasons to Be Pretty Happy” that was scheduled to run this summer. “MCC Theater is canceling the upcoming production of ‘Reasons to be Pretty Happy’ by Neil LaBute and is terminating his tenure as its playwright-in-residence, effective immediately,” the theater said in a statement issued Thursday. “The Theater will be announcing a new play to complete the current season in the coming weeks.” Reps for the theater offered no further explanation for the abrupt termination, and...