OMG! Chris Brown, Karrueche Tran Split

Chris Brown is officially back on the market.

After a complicated year-long romance, the "Don't Wake Me Up" singer, 23, and aspiring model Karrueche Tran have ended their romance.

"I have decided to be single to focus on my career," Brown tells Us Weekly. "I love Karrueche very much but I don't want to see her hurt over my friendship with Rihanna. I'd rather be single allowing us to both be happy in our lives."

PHOTOS: Rihanna and Chris' romance

Indeed, Tran, 23, entered the public spotlight in February of this year --after Us Weekly broke news that Brown was secretly hooking up with his most famous ex-girlfriend Rihanna, 24. ...