Ryan Cabrera and Riley Keough break up?

"At the end of the night, Riley searched all throughout the crowd and headed back to the bathrooms [for Ryan]," the source tells OK!. "The women's bathroom was locked, but she heard Ryan in there and so she forced the door open and saw Ryan in the bathroom with his ex-girlfriend from Texas."

Upon discovering them, the 18-year-old model "cried and yelled" before leaving. Ryan, 25, though, never followed suit.

However, a rep for Riley denies the report.

"This is not true," she tells OK!.

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