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Designer MARC Jacobs - who has been in and out of rehab over the past two years has pals worried, PAGE SIX reports.

Hunky Jacobs showed up to the Costume Institute Gala two hours late with yet another nameless young man in tow.

"He spends most of his time partying until morning in Paris," a friend said. "It's out of control. There's always a different boy and everyone is worried he's going to pull a Halston" - referring to the designer who died of AIDS in 1990.