Nicki Minaj and Meek Mill broke up after a nuclear fight during her birthday weekend last month ... and it wasn't about cheating.
Sources close to the ex-couple tell us ... they weren't getting along in Turks and Caicos, because he was hanging with friends and not paying attention to her. She went nuts on him, he got pissed and left the island without her, and she said, "Screw this," and ended the relationship. Just that simple.
There are reports Meek had been cheating with a woman named Sonye Rasool and that's what set off Nicki. Sonye claims she and Meek hooked up years before Nicki, but fully denies any cheating and adds ... she's about to file defamation lawsuits against several outlets.
She also says she understands truth is a defense, but has no fear.
It's interesting ... the breakup appears to be over the small stuff, which makes you wonder if the door is still open.