Justin Bartha films "The Rebound" in New York last May. (©WireImage.com)

During their recent sit-down on "Oprah," Mary-Kate asked twin sister Ashley what quality she likes most in a man. Her response: "Probably loyalty." But it seems she's not looking for an until-death commitment from actor-beau Justin Bartha just yet. "Contrary to several tabloid reports, Ashley Olsen is not engaged to be married," her rep assures People. "Ashley is dating Justin Bartha and they are very happy." Last week, the National Enquirer alleged that the teeny mogul, 22, and her 30-year-old boyfriend of seven months were planning to get hitched next summer in a "secret" million-dollar ceremony on the French Riviera. "She wants to take her vows under a canopy of exotic white flowers as the sun sets behind her at the super-exclusive Hotel du Cap Eden Roc," enthused a snitch. "The place is for the fabulously wealthy and accepts only cash -- no credit cards." Other "I do" details from the apparently fictional nuptials included a $250,000 custom wedding gown created by Ashley's creep-tastic designer-pal, Karl Lagerfeld; a private jet to fly in guests (estimated cost: $150,000); luxury suites for them to stay in ($400,000); a taco dinner catered by her favorite Mexican eatery in New York ($100,000 -- hey, guacamole ain't cheap); a honeymoon in Greece ($100,000); and bowls of the bride's favorite sugary treats -- Twizzlers, Tootsie Rolls, Sour Worms, Sour Patch Kids -- set out at the reception.

Mary-Kate just stands there as she signs copies of "Influence," the coffee table book she co-wrote with sister Ashley, in New York on Oct. 28. (©WireImage.com)

In related Olsen twin news, Mary-Kate told Oprah, "I'm not in a relationship," but it seems she's still hanging out with artist Nate Lowman, whom she started seeing this time last year. According to People, the twosome turned up at New York nightclub RdV to catch the Accompanied Literary Society's reading of a recently unearthed work by Edgar Allan Poe. MK must have been blown away by the material, because a spy tells the mag that she "literally just stood by the deejay booth -- didn't dance, didn't drink, just stood there for an hour and a half."

Brooke Mueller and Charlie Sheen hit the Emmys in Los Angeles last September. (© Retna Ltd.)

MK's idle state was apparently a lot like how Charlie Sheen acted during a quick trip to Las Vegas, at least according to his rep, who adamantly denies a report in the current issue of Star that accuses him of walking out on his twin boys-incubating wife, Brooke Mueller, and partying in Sin City. The tab contends that the couple, who wed in May, has been "fighting relentlessly," which prompted Sheen to take off for a booze- and lap dance-inclusive getaway. But the "Two and a Half Men" star's flack denies he's reverted to his bad-boy past, insisting that his Vegas stopover was professional and perfunctory. "Star magazine never lets the facts get in the way of a good hatchet job," fumes the spokesman to Us. "Had the reporter bothered to check, he or she would have learned that the reason Charlie was in Vegas [on Oct. 25] was for a contractual appearance on behalf of Planet Hollywood's Prive." What's more, says the rep, "Charlie was in Vegas only four hours. He arrived and left the same evening, not on Oct. 28, as Star reports. Star's reporting of his alleged behavior is as inaccurate as the rest of their story." (That sigh of disappointment you hear is likely coming from the general direction of Denise Richards, the second Mrs. Sheen and the mother of his two daughters.)

Friends don't let friends make out with Tila Tequila, which is something Justin Long's pals should remember if his busy lips start to pucker up again. According to the New York Post, the actor-cum-Mac Guy, who segued from his saliva-saturated relationship with Drew Barrymore to a dalliance with Kirsten Dunst, got hands-on with the bisexual "Shot at Love" punch line at a Las Vegas hot spot on Halloween. An eyewitness picture-paints to the paper that Long "asked her to straddle him while making out. Eww." Perhaps Tila was just testing out the theories put forth in her new book, "Hooking Up With Tila Tequila," which -- mark those calendars, people -- hits stores next month. "Here's the best secret weapon I can give you: Hold off on having sex," she writes in the sure-to-be life-changing tome (via the Post). "Give him a little taste, but not too much ... Keep him drooling." And when the test results come back the time is right to consummate your love, "Get crazy!" advises Tila. "[Bleep] like a porno star!"

Terri Seymour and Simon Cowell attend the "American Idol" Season 7 grand finale in Los Angeles last May. (©Retna Ltd.)

For any of you brave ladies out there who were hoping for a chance to run your fingers through the shag rug that sits atop the newly single Simon Cowell's chest, you may have to wait a little while. The "American Idol" judge, who just split from Terri Seymour, his girlfriend of six years, tells the London Daily Mirror that he's avoiding the opposite sex for the time being. "Don't worry about me -- I don't need a lonely hearts ad," he assures the paper. "I'm off women now." Simon adds to FoxNews.com that his "Extra" reporter ex "wants a different path in life, and I totally respect her for it." Still, he admits, "I find women confusing, really. When you hook up and date, you're both honest about what you want. I have never ever said that I want children or marriage. I know some people find it hard to fathom, but it's me, it's who I am. Bottom line is I am married to my job." Meanwhile, Cowell insists to the Mirror that "everything's fine between me and Terri -- we're still friends," and he points out that despite his reputation as a dream-destroying meanie, "I've always been very close to all my ex-girlfriends. We've never fallen out -- they're like my best friends." Perhaps that has something to do with the way he says goodbye. Life & Style claims that Simon sent Seymour off into the sunset with a $4 million house in Los Angeles and a lump sum payment of $5 million.

Next: Breakup Bits: McGosling Kaput Again? Manson Dumped?