John Mayer, Katy Perry Get Affectionate, "Rock Out" at Rolling Stones Concert

USMagazine, Friday, December 14, 2012, 5:00pm (PST)

Mick Jagger was right -- "Love Is Strong," and so is Katy Perry and John Mayer's blossoming romance.

On Thursday, Dec. 13, one day after she introduced Mayer as her "boyfriend" to the cast of Broadway's A Christmas Story, the "Wide Awake" singer, 28, accompanied her man to a Rolling Stones concert at Newark, New Jersey's Prudential Center, where they both enjoyed and put on quite a show.

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Arriving at the venue shortly before the event started, the couple held hands as they mingled with the band backstage. While Mayer, 35, chatted up Keith Richards and Ron Wood, his pop star girlfriend smiled and laughed adoringly, a witness tells Us.

A short time later, Perry -- in a black blazer, T-shirt, printed scarf, and black pants -- was escorted to the pit while her beau stayed behind to tune up his guitar. After joining the band onstage to perform "Respectable," the star headed down to enjoy the rest of the concert with his on-again love.

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"They rocked out," an onlooker says of the pair, who've been going strong ever since reuniting in September after a brief separation. "They were especially excited during 'Miss You' and 'Start Me Up,' but they were so into the whole show."

And so into each other. The couple stayed close all night, with Mayer leaning in occasionally to whisper into the "Firework" singer's ear.

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Earlier in the week, Perry bonded with her beau's father, Richard, at a performance of A Christmas Story in New York City. Backstage, she chatted happily with the cast -- many of whom are children -- while Mayer hung back and watched.

"You would think he was just a supportive boyfriend," an insider told Us of the singer, whose exes include Jennifer Love Hewitt, Jessica Simpson, and Jennifer Aniston. "He let her be the star."

This article originally appeared on Usmagazine.com: John Mayer, Katy Perry Get Affectionate, "Rock Out" at Rolling Stones Concert