sunglasses Simon Cowell

Where the heck is Simon Cowell's fiancee, Mezhgan Hussainy?

The celebrity makeup artist was rumored to be vacationing by her man's side on his rented yacht in St. Barth, but so far, we've only seen pix of the music mogul getting cozy with gorgeous New York socialite Lauren Silverman. The stunning brunette happens to be married to real estate and gaming mogul Andrew Silverman who's Simon's BFF, according to a rep for the X Factor!

Cowell and Mrs. Silverman appeared to be flirting with each other while on the deck of the 196-foot yacht, which costs $600,000 a week to rent, btw!

And just after we snapped these photos of the X Factor honcho getting close with Silverman, Cowell invited ex-girlfriend Sinitta to join them on the boat.

Cowell was just with his ex in Barbados and now she's followed him to this French Caribbean island to continue the vacay. Check out the similarities between Sinitta's pose and Lauren's pose with Simon last week ... hmmm ... photo op, anyone???


Since Simon's close encounter with Lauren made headlines, could Sinetta's invitation be strategic on Simon's part?

Looks as if what happens in St. Barth is definitely NOT going to stay in St. Barth!