Roundup: Celebrities Break Up and Make Up in 2011

We've barely rung in 2011 and already celebrity breakups, engagements and marriages are in the news- and in a big way.

First up, Skid Row front man Sebastian Bach- most recently known for his stint on "Celebrity Fit Club," and Maria Bierk, his wife of 18 years are calling it quits. Although Bach acknowledged he and his wife had been separated since April, the split comes as somewhat of a surprise to longtime fans. The couple appeared together on VH1's "I Married Sebastian Bach."

Meanwhile, rocker John"Cougar" Mellencamp and his wife, model Elaine Irwin Mellencamp, have separated. The Mellencamp's have been married for 18 years, dating way back to the rocker's early days as an MTV video star.

And following an eight year relationship, actors Macaulay Culkin and Mila Kunis have also split. A rep for Kunis, who is currently in the movie "Black Swan," called the split "amicable." But it looks like Culkin will be home alone again, after all.

On a happier note, actress Valerie Bertinelli and her longtime love, Tom Vitale were married in a New Year's Day wedding. And the guest list was really all in the family- even Bertinelli's ex-husband, Eddie Van Halen, attended the shindig.

Also on New Year's Day, Shania Twain and Frederic Thiebaud wed in Puerto Rico. She and Thiebaud linked up after their former spouses allegedly had an affair. Suffice it to say, Shania's ex-husband, Mutt Lange, probably didn't attend this shindig.

Meanwhile The Hollywood Gossip is speculating that reconciliation may be in the works for country star Billy Ray Cyrus and his wife, Tish. While a smiley lunch at P.F. Chang's is the only indicator thus far, at least they're on speaking terms!

Amidst rumors that David Arquette hopes to get back together with wife Courteney Cox (the couple separated last fall), the actor recently checked into rehab - and he has his estranged wife's full support. Could this be the first step towards reconciliation for the couple?

And if all you wanted for Christmas was a sparkly engagement ring, you were in good company.

84 year old Playboy founder, Hugh Hefner, popped the question to his twenty-something year old girlfriend, Crystal Harris, while Eddie Cibrian prepared to make an honest woman out of Leeann Rimes.

Both Reese Witherspoon and Natalie Portman got engaged, too, while Poison front man Bret Michaels- a lifelong commitment-phobe- finally proposed to his long-suffering girlfriend, Kristi Gibson (I say long suffering because she had to sit through three seasons of VH1's "Rock of Love" while her man made out with other women).

But Michaels did his proposal the classy way- or at least the only way a reality TV star knows how: with the cameras rolling. So now their kids, Raine and Jorja, can forever see the tape of the day that Mommy and Daddy got engaged. Rock on!