Sources with direct knowledge tell TMZ, the split has nothing to do with cheating. We're told this "is a long time in coming" -- the 2 have been growing apart for a long time. As one source put it, "They're just disconnected from each other."

We're told if you look back at Cardi's posts from December, she said, "You know when you just out grow relationships ... I'm tired of protecting peoples feelings ... I GOTTA PUT MYSELF FIRST!"

Our sources say they tried to work things out the first part of the year, but the distance between them just kept growing.

We're also told the split is "amicable." We've learned Cardi has already hired a divorce lawyer who has filed the case. She's asking for primary custody.

Our sources wanted to make it clear ... this was "not an overnight decision," but something that has been brewing for a long time.

TMZ got photos of Cardi in NYC Wednesday, trying hard to cover up with the help of multiple umbrellas.

Page Six first broke the news they were divorcing.

BTW, Cardi filed for divorce once before in 2020, but withdrew the docs. Our sources, however, say this time she's not changing her mind.