Does the couple that racks up the frequent flyer miles together stay together? Hot on the heels of their touchy-feely holiday in Rome, Jessica Simpson and John Mayer have taken their mushiness and matching chocolate manes Down Under, where he's on tour for the next several days.

The former Mrs. Nick Lachey, 26, was spotted grooving backstage to the mellow song stylings of her shaggy haired honey, 29, as he played a music festival this weekend in Perth, Australia, according to the Sunday Times.

Noticeably absent from their recent getaways? Jessica's creepily ubiquitous dad Joe Simpson.

"When she was with Nick, she was really under her family's thumb," a "friend" tells People. "This is a relationship that is all hers."

That's not to say the Simpson clan isn't still tight.

Father and daughter recently visited a Mexican orphanage so she could donate a Chrysler she won in a celebrity raffle, and she's making sure little sister, Ashlee, gets to know her new beau.

"Ashlee loves John," a Simpson source tells the mag. "She thinks he is great for her. More importantly, Jess is happy."

Not just happy, adds another insider, but "Ashlee said Jessica is the happiest she's ever been in her life."

Yet another Simpson snitch helpfully chimes in for Mayer, saying he "seems very smitten."

And if by "smitten," the mole means "totally hot for," that might explain the chin-dimpled duo's extended saliva-swapping session at a Los Angeles concert on March 21, which was later followed with oodles of handholding and chuckles as they enjoyed cocktails with Ashlee.

"Jessica looks really comfortable with him," opines an observer, with her pal Christina Milian adding, "Clearly this is a relationship that's not for the cameras. It's not about celebrity. It seems like they truly have an attraction to each other, and they're both clearly very talented as well."

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