John Mayer Does Best 'Supportive Boyfriend' Impersonation

Here's John Mayer touching down at New York's JFK airport on Saturday, where he'll join girlfriend Jennifer Aniston for her latest publicity round. 

Fresh on the heels of his latest relationship blunder, the crooner is set to decorate Jen's arm during her string of Marley & Me premieres, the first of which he attended in L.A. on Thursday. 

And according to insiders, John's face-saving comes as a pleasant surprise to Jen, who was plotting a plan B during the wake of their August split.  Page Six says:

'A few months ago, during a brief split between the duo, Aniston's camp was shopping for potential dates. "She didn't want to face the glare of being unattached while Brad Pitt toted Angelina Jolie around" on the promotional rounds for his release of "The Curious Case of Benjamin Button."

Aniston "did not want to be single when her movie opened," one source said. "A friend of her agent was calling around asking for young men whom they could set her up with." But the attempt to find a replacement for Mayer was aborted when he and Aniston soon got back together.'

And not only has John been showing up for Jen, but he's been paying her darn good lip service too.  He was heard gushing to reporters at the L.A. premiere: 'I'm here to support my girl.'

So waddaya think folks: is the Mayer man redeeming himself?