|Ashton Kutcher and Rumer Willis|
An onlooker said: “Ashton came on his own and he was there from the beginning to the end. He provided a real cool, unassuming, supportive and stable presence for Rumer, who was obviously a little nervous.
“Ashton and Rumer had a short talk before she went on stage and you could tell he was pepping her up and building her confidence and then when she started singing his whole face lit up.
“He was obviously really, really proud of her and was smiling throughout her performance. I even saw him singing along at one point.”
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Following the hit-packed set, Ashton greeted Rumer with a “huge hug” and the pair spent the rest of the night “huddled together” in deep conversation.
The source added to RadarOnline.com: “As soon as Rumer finished she headed straight to Ashton. He gave her a huge hug and then they were huddled together talking for the rest of the night. “Despite what’s happening with Demi, it’s obvious he and Rumer are still very close, it was really sweet to see.”
After receiving treatment for "an eating disorder and addiction issues" at a rehab facility in Utah, Demi is said to be feeling “great” and is ready to get back to work.