Carole Radziwill Leaving 'RHONY' Because of Bethenny Frankel

Carole Radziwill's announcement she's leaving 'Real Housewives of NY' due to "frenemies" is a not-so-thinly veiled shot at Bethenny Frankel ... TMZ has learned.

Sources close to the 'RHONY' cast tell TMZ ... Carole feels like Bethenny is el jefe when it comes to cast members. She's, quite simply, the dominant personality, but after Carole and Bethenny had a falling out in the Spring ... Carole felt blackballed, in a way.

Our sources say BF controls the show and used her power to push Carole out of the picture ... effectively reducing her camera time. Behind the scenes, we're told, other cast members refer to 'RHONY' as 'The Bethenny Show.'

We've reached out to Bethenny ... but no word back yet.

In the end, Carole's gonna be just fine after her 6 seasons on Bravo -- we're told she intends to focus on writing projects better suited for her "more steady temperament," and so far she's got 3 in the works.