Getty Images North America 1 / 12
Getty Images North America 1 / 12

They just can't quit each other.

Katy Perry and John Mayer are giving it another go ... again.

The on-again, off-again duo has reunited (for the umpteenth time) and the singing superstars are hitting the romantic ground running.

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"They never stopped talking and being friendly while they were broken up," a source told E! News. "They are really excited about being together right now and spending as much time as possible. ... They have spent almost every night together this week."

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And that included a recent double date with "Girls" star Allison Williams and her fiance Ricky Van Veen at Chateau Marmont in West Hollywood, Calif., where the reunited pair greeted each other with a kiss and held hands under the table, according to reports.

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"They actually buried the hatchet a while back, and they are friends," a Katy source told People recently, saying Katy "is focused on her career and making herself happy."

Katy may have alluded to the reunion in a cryptic New Year's Day tweet when she wrote, "Happy New Year. I love a fresh start."

Best of luck this time around.