Just weeks after rumors of a Robert Pattinson-Kristen Stewart reunion surfaced, onetime K-Stew co-star Riley Keough has completely put rumors of her own R-Pattz romance to rest for good -- in a big way.

Us Weekly reports that Keough is back on with her ex fiance, Alex Pettyfer.

The pair, who broke up last year, were spotted holding hands at the Los Angeles premiere of 'The Butler.'

"There was definitely warmth between Riley and Alex," a witness told Us Weekly. "They were laughing together and smiling at each other." The source added, "They definitely came together."

Keough and Pettyfer first got together in October 2011, a time during which they were described as "inseparable," and were engaged six months later.

And they may be engaged again: The source noted that Keough was rocking a rock on the all-important finger.

Robsten shippers, rejoice!

More From StarCrush