Trouble in paradise for Simon and Mezhgan: Sinitta's tweet alludes to friction on holiday

A romantic vacation in Barbados probably seemed like the perfect way for Simon Cowell and his fiancé Mezhgan Hussainy - finally reunited after some time apart - to smooth over any rough patches in their relationship.

But it appears things haven't gone to plan for the couple.

The sticking point seems to be that the pair aren't alone on their getaway – a group of Simon's friends – including his ex girlfriend Sinitta, are also there.

Eyebrows were raised when Simon departed for the Caribbean with Sinitta, leaving Mezhgan in London.

Five days later Mezhgan arrived. And, according to the Daily Mail, has asked that Sinitta not be invited on Simon's yacht on New Year's Eve – giving them a romantic night alone.

The singer – pictured below with Simon and another of his exes Jackie St Clair at Ascot last year - seemed to allude to friction in a tweet posted a few hours after the X Factor producer's American girlfriend arrived.

She wrote: "If this was Dynasty, I seem to have found myself cast as Alexis! Against type but a great role. So lights, camera - action!"

There are increasing reports that Simon's relationship with Mezhgan is on the rocks. He proposed in February, but after the 37-year-old moved into his Beverly Hills home things are said to have cooled.

And in the last few months, with Simon based in the UK during the X Factor and Mezhgan working in America, there's been little chance for them to see each other.

Simon's publicist Max Clifford insists things are fine between them, however. "She is in the US a lot as that is where she works. He understands that as he is a workaholic himself."

But when asked about the engagement he adds: "I would be surprised - but delighted - if he ever gets married."