Oh snap!  This is interesting! Nikki Reed is hooking up w/ Derek Hough, while she is STILL married to Paul McDonald!  (Yes, we know they split up, but technically she's still married! 

US Weekly broke the story:

Reed, 25, and Hough, 28, were most recently spotted making out at Rock & Reilly's in L.A. on April 18, an onlooker tells Us. The duo were joined by Hough's DWTS best friend Mark Ballas and costar Cheryl Burke.

"The whole group was drinking and partying. Derek bought shots for Nikki at the bar," the eyewitness tells Us. "There was lots of PDA, Nikki was feeding him, holding hands, and they left together." The onlooker adds: "They didn't seem to care if anyone was watching."