The 37-year-old has told Cowell that his former flames, including Sinitta and Terri Seymour, will not be among those close friends who see in the New Year with their yacht party. The Mirror claims that Hussainy remained in London to oversee the refurbishment of the X Factor judge's home, while he went to Barbados with the 'So Macho' singer and other friends.
However, despite booking Hussainy first-class travel to join them, Cowell was told: "It's me or them".
"Simon and Mish haven't spent much time together of late, but Simon has vowed to give their relationship another shot and give her his all," a source said. "He originally tried to fly her out on his private jet but that got grounded so she flew first-class on a standard 747 instead. Simon greeted her with champagne and they had a romantic supper together on Tuesday evening.
"But one of the conditions she put down is that Sinitta b*llocks off out of the way. She wants time alone with her man."
The source added that Cowell told his guests that they would be leaving on December 30, so that he and Hussainy could celebrate alone.
"Simon has agreed, and now he and Mezhgan will be celebrating New Year's Eve together on his yacht, the Slipstream," the source revealed. "But, Simon being Simon, he won't ditch the harem altogether. Instead, they are all meeting up on January 1.
"Mezhgan is happy with this arrangement and accepts that Simon is compromising massively... for him."
They added: "It's not been easy, but Simon and Mezhgan are very much back on and looking to make a go of things."
> Hussainy: 'I'm still with Simon Cowell'