Demi Moore’s friends have said the actress is “sick to her stomach” over claims Rihanna “hooked up” with her estranged husband Ashton Kutcher, after the singer was seen leaving the actor’s house at 4:00 a.m.

According to a source, the story of Rihanna and Ashton Kutcher’s romance has “sent Demi spiralling”, leaving her friends concerned for the wellbeing of the actress, who only left rehab last month.

The source told Grazia magazine: “Demi is constantly keeping tabs on Ashton so when these pictures came up she was understandably devastated. Demi’s convinced something happened between them and said she felt <<sick to her stomach>>.”

Although Ashton Kutcher has been seeing other girls, none of them have been high profile, so the thought of him hooking up with someone as famous as Rihanna left Demi Moore reeling.

“Demi’s been acting crazy ever since, trying to find out information about the pair,” said the source.

“Demi is in such a fragile state, even the idea of them together has affected her quite badly. She’s in a terrible way but, at the end of the day, Ashton is a single man and free to do whatever he likes.”

The story of Rihanna and Ashton Kutcher's romance has “sent Demi Moore spiralling”, leaving her friends concerned for the wellbeing of the actress

Another source said that Demi Moore has been left “humiliated” because Ashton Kutcher appears to have moved on so quickly after her time in rehab following their marriage split.

The source told Closer magazine: “Demi can’t believe Ashton would do this.

“She’s really hurt by the rumors and feels humiliated he’s being linked to other celebrities just a few weeks after she got out of rehab.

“She feels it cheapens their marriage even further.”

The claims surrounding Rihanna and Ashton Kutcher’s relationship come as the singer was seen keeping her head down while boarding a flight at LAX.

Rihanna, 24, wore an all-black ensemble, a leather jacket and a grey hooded jumper, teamed with a BOY London baseball cap and black Adidas trainers.

The pop star has so far remained tight-lipped on reports that she and Ashton Kutcher have in fact been seeing each other for eight weeks.

Rihanna has reportedly been enjoying late-night trysts with Ashton Kutcher after hitting it off with him at a friend’s party in December.

She is apparently so besotted with him, that she’s asked about joining his Kabbalah group.

Rihanna was spotted by a photographer as she drove up to Ashton Kutcher’s property with her security team around midnight on evening last week.

The snapper confirmed to TMZ that Rihanna arrived almost bang on midnight, and didn’t leave until roughly 4:00 a.m.