The boyband has been on hiatus for the last two years while the siblings pursued solo projects, but they returned to the spotlight for a sold-out one-off concert at Radio City Music Hall in Manhattan.
During the show, the brothers combined their hits with their solo tracks and debuted new music from their upcoming album, with Nick telling the audience he struggled to write the personal lyrics of a track called Wedding Bells.
He told the crowd, "We're in the process of recording a new album, which is both good and bad... (we have to) dive into subjects that make us uncomfortable and write about them... You have to write a song and apologise for it later. I don't think I've ever written a song that makes me as uncomfortable as this song does. Some things happened in the last year that affected me in that moment... This song is called Wedding Bells."
According to MTV.com, the song features the lyrics: "She says, 'Can you keep a secret/ A ceremony's set for June/ I know it's a rush, but I just love him so much/ I hope that you can meet him soon'..."
He later sings, "I don't want to love, if it's not you/ I don't want to hear the wedding bells bloom/ Maybe we can try one last time/ But I don't want to hear the wedding bells chime."
The candid lyrics have sparked rumours Nick wrote the song about his ex-girlfriend Cyrus, who recently became engaged to Australian actor Liam Hemsworth.
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