EXCLUSIVE

Lisa Vanderpump may bail on 'Real Housewives of Beverly Hills' ... TMZ has learned.

Sources close to production tell us ... Lisa's the only 'Housewife' who hasn't signed on for a 7th season. She's complained to producers she didn't dig the "negative vibes" last season from castmates who ganged up on her.

She met with producers early last week at Pump, and added a concern -- time. She spends most of it focused on "Vanderpump Rules" as well as operating her 3 restaurants.

And there's more ... Lisa's on a mission to end the dog meat market in China, which also eats into her time.