Tiffany says relationship with NKOTB's Jonathan Knight caused 'rift' between her ... American Music Awards New Kids on the Block drop '80s Baby' video with behind-the-scenes look at The Mixtape ...

The series follows Jonathan, his husband Harley ... a member of New Kids on the Block since the late '80s. And now, even more ...

But the were some heartbreaking reasons that led Jonathan to go on a long ... she admitted to Andy Cohen that she and Knight ...