(Cover) - EN Showbiz - Demi Moore and Ashton Kutcher's relationship is unsalvageable, a source has revealed.

Ashton has been accused of cheating on wife Demi on their sixth wedding anniversary with Sara Leal at the Hard Rock Hotel in San Diego last month.

Ashton and Demi have kept a low profile in recent weeks. The couple was seen out together only once at the Kabbalah Centre in Los Angeles on September 30, appearing tense and leaving in separate cars.

According to an insider, the damage the couple has endured is irreparable.

"They've been in counselling," a source told RadarOnline.

"They separated about six weeks ago. Both went to Kaballah counselling hoping to save the marriage. But it's over now."

Demi is thought to be shattered by the adultery rumours.

"She is completely stressed out," the source said. "She's devastated."

Neither Ashton nor Demi have yet to publicly discuss the rumours about his alleged affair.

The pair have been leaving cryptic Twitter messages on their mutual accounts. Ashton included a link to the Public Enemy track Don't Believe The Hype on his, while Demi posted a picture of herself with her eyes shut and the caption; "I see through you."

Sara has had meetings with attorney Keith Davidson and is thought to have been requesting a six-figure sum from Ashton to keep quiet about their alleged liaison. (C) Cover Media