Danny Kedem, 30, informed Weiner of his resignation, The New York Times reported Sunday.
Kedem and a spokeswoman for Weiner's campaign declined to comment on Kedem's resignation, which comes after Weiner's admission last week he texted sexual content to women even after he resigned from Congress in 2011 over the practice.
Weiner claimed he had undergone therapy and said the incidents are "behind me."
"Now citizens have to decide whether this personal behavior -- when one thing happened or it didn't happen -- is important to them," he said.
Swim Week Miami Beach 2014 [PHOTOS]