Kutcher was seen partying at Madonna's annual post-Oscar party but his estranged wife Demi Moore was nowhere in the picture, reports radaronline.com.
Moore and Madonna are known as best of friends and the former even played a host at the 2011 Oscar bash.
A source present at the party said: "When Ashton walked in, it got the crowd buzzing. Madonna's never spoken about the split, but it's obvious she's sided with him over Demi."
"It was kind of shocking as Demi has even hosted the party.