It looks like the 26-year old's cool demeanour has finally cracked after showcasing some rather odd behaviour at a New York bar by drilling a hole into a table on Monday night.

Robert is legally required to appear with Kristen at the upcoming LA screening of The Twilight Saga: Breaking Dawn - Part 2.

But the stress of the looming premiere looks like it has been taking its toll on Rob who looked tired and withdrawn as he made his way through Manhattan.

Robert and Kristen have not been pictured together since news broke of her relationship with Rupert Sanders in July, when photos of the pair locked in an intimate embrace were published by Us Weekly.

The Twilight co-stars reportedly moved out of their shared LA home after the incident.

A source tells RadarOnline: 'Rob and Kristen are legally required to promote Breaking Dawn Part 2 together along with the rest of the cast.

'Their individual contracts have very specific language about what is legally required of Rob and Kristen to do on the publicity tour.'

The insider added: 'The studio execs at Summit weren't happy when Rob and Kristen broke up, but this is why there are clauses about what is required of the stars to do.'

The November 15 date is not the only promotional event the pair will have to endure.

Robert, Kristen and the Twilight cast are scheduled to embark on a worldwide media tour to promote the final film in The Twilight Saga.