|Robert Pattinson and Kristen Stewart|
The 'Twilight' duo was lined up to appear as presenters at the MTV Video Music Awards in Los Angeles next month.
But Kristen, 22, is now heading to the Toronto International Film Festival to promote her movie 'On The Road' instead.
Their appearance would have been the first time they have been seen together in public since her fling with married 'Snow White and the Huntsman' director Rupert Sanders, 41, was revealed.
Insiders say 26-year-old Robert will now attend the show alone.
An awards source told the Daily Mirror newspaper: "Bosses were hoping that Kristen and Robert would be surprise guests before this scandal blew up.
"The idea was for them to jointly present awards...but that has been changed."
Robert was mobbed by fans as he promoted his latest movie 'Cosmopolis' in New York.
He ducked questions about the scandal, adding: "I have never been interested in selling my personal life. That is the reason you go on TV."