Cardi B Announced Offset Split 2 Days After Alleged Texts Imply He was Cheating

The timing of Cardi B's shocking announcement that she and Offset had split is interesting, because it came shortly after alleged text messages leaked showing he was looking for a threesome ... and not with her.

As we reported ... Cardi revealed the rappers -- who wed last year and had a kid together in July -- have been trying to work things out for a long time but decided to call it quits. She says they're still friends and biz partners ... but are no longer in love.

The reason for the lost love is now a topic of speculation ... being fueled by texts Offset allegedly sent to a woman who goes by Summer Bunni asking her to hook up a ménage à trois with another female rapper, Cuban Doll.

The scandalous leak -- which sources tell us was orchestrated by another woman who had a falling out with Cuban -- also included a photo of a FaceTime convo with Offset.

Oh yeah, and Offset's texts appear to be from June 28 ... just a couple weeks before Cardi gave birth to their daughter, Kulture.

So far, neither Cardi nor Offset have addressed the cheating allegations, but as we reported ... he commented on Cardi's video announcing their split with "Y'all won."

Still unclear who y'all is ... or what they won.