MARY J. BLIGE FILES FOR DIVORCE FROM HUSBAND/MANAGER

Mary J. Blige just pulled the plug on her marriage to her husband/manager ... filing for divorce to end her 12 year marriage, TMZ has learned.

Blige just filed docs seeking to end her union from Martin "Kendu" Isaacs -- who she married back in 2003. Blige lists the date of separation as "to be determined" -- unclear why.

Blige cited irreconcilable differences as the reason for the split. The couple has no children together.

There is one interesting note ... Blige is asking the judge to block Isaacs' ability to get spousal support. The document does not say if there is a prenup.

We reached out to Blige and Isaacs -- so far, no word back.

Unclear what went wrong -- but back in 2014, Blige talked about the challenges of dating her manager during an interview with Stella Magazine.

"He always has my back -- he’s going to fight to the death for Mary J Blige. The downside is that there’s no separation -- it’s on all the time."

"When you don’t feel like answering to your manager, he’s still your husband. If one of you doesn’t want to talk about something right now, you have to respect that. And you have to respect each other’s space."

Blige also famously banned Isaacs from having friendships with other women.

"All females for me, all guys for him. There’s none of that, 'Oh, that’s my female friend. Oh, that’s my guy friend.' No. Not in a marriage, I’ve never seen that work."