AceShowbiz -

During a New Kids On The Block concert on Thursday night, April 4 at the iHeartRadio Theatre in New York City, the boyband's member Jonathan Knight walked off the stage halfway through their hour-long performance. He made his exit as the group was about to sing the ballad "Survive Again", where the 44-year-old singer supposedly sings a part in.

As brother Jordan Knight, Donnie Wahlberg, Danny Wood and Joey McIntyre got ready to sing the new song from their album "10", Jonathan positioned himself behind his sibling, prompting McIntyre to chide Jordan to pull his brother up in front. Looking visibly agitated, Jonathan just continued to look down and pace around onstage as Wahlberg tried to make him feel comfortable by joking that one of the fans watching even took out her kids' college fund to buy tickets to the show.

Despite his bandmates' encouragement and the crowd's cheers of support, Jonathan walked off stage and never returned again for the rest of the gig. The incident was linked by some to a particularly difficult bout with social anxiety, a disorder that he has had since his childhood and something which he had openly talked to Oprah Winfrey about in an interview back in 2001.

After the show, Jonathan tweeted, "I'm sorry," and was back on his feet the next morning, singing "We Own Tonight" on the "Today" show with the rest of NKOTB without any problems.