After reports that CHRIS BROWN and RIHANNA hooked up in a nightclub bathroom, Chris Brown is one girlfriend short.  Karrueche Tran has reportedly broken up with him.

A source says, "She finally had enough and dumped Chris for good.  She and Chris had been on thin ice for a while . . . The relationship was tumultuous and filled with drama, and she just had enough, and wants a healthy relationship."

Meanwhile, TMZ has photos of Chris and Rihanna together at that club Monday night.

As well as a picture of Chris leaving Rihanna's hotel several hours later. 





And it looks like they also hit up the JAY-Z concert last night.