I Love You, I Love You Not: See the Top On-Again, Off-Again Celeb Couples

Is the third time the, uh, charm? Robin Wright Penn has reportedly filed for divorce from Sean Penn, marking the third time in nearly two years the couple has split up. (TVGuide.com's calls to the couple's rep were not immediately returned.)  But the Penns aren't the only stars with divided hearts. Check out these other celebrity couples who break up to make up to break up to — you get the picture.
Sean Penn and Robin Wright Penn
First got together: 1989; married in 1996
Number of splits: Three; most recently this week
The Penns started divorce proceedings in December 2007 only to call them off four months later. This past April — two months after a tearful Wright Penn watched her husband win his second Oscar for Milk — Penn filed for legal separation. He rescinded that petition in May. He also took an acting sabbatical to focus on his family. Now, Wright Penn has reportedly filed for divorce, citing "irreconcilable differences."
Travis Barker and Shanna Moakler
First got together: 2002; married in 2004
Number of splits: Three; most recently in April 2009
Who can keep track of these crazy kids? Especially when they're photographed holding hands one day and cursing each other out on MySpace the next? The two have reunited twice since Barker filed for divorce in August 2006. The most recent reunion was after the drummer's September plane crash. They split again in April after Barker accused Moakler of cheating on him with Gerard Butler.
Kate Hudson and Owen Wilson
First got together: 2006
Number of splits: Three; most recently in April 2009
This blonde pair started dating in 2006 after filming You, Me and Dupree and split in June 2007. They reunited for a few months in 2008 and earlier this year, but perhaps they've struck out for good. Hudson's been canoodling with Alex Rodriguez lately.
Melanie Griffith and Don Johnson
First got together: 1972; married in 1976 and again 1989-1996
Number of splits: Two; most recently in 1996
Talk about young love. A 14-year-old Griffith and 22-year-old Johnson hooked up after meeting on the set of The Harrad Experiment, starring Johnson and Griffith's mother, Tippi Hedren, and briefly married in 1976. Thirteen years later, they remarried after Griffith found out she was pregnant with daughter Dakota. They divorced in February 1996 and Griffith married Antonio Banderas three months later.
Sienna Miller and Jude Law
First got together: 2003; engaged in 2004
Number of splits: Two; most recently in 2006
Perhaps she should've seen it coming. Miller and Law got together during the production of Alfie, in which the actor plays a womanizing cad. Oh, how life imitates art. In July 2005, Law publicly apologized for cheating on Miller with his children's nanny. The two split and tried to make another go of it before ending their roller-coaster romance in 2006.
Sarah Silverman and Jimmy Kimmel
First got together: 2003
Number of splits: Two; most recently in March 2009
Matt Damon and Ben Affleck had nothing to do with this. The funny couple split in summer of 2008, but reconciled in the fall. They survived winter, but romance wasn't in full bloom by spring.
Jennifer Aniston and John Mayer
First got together: April 2008
Number of splits: Two; most recently in March 2009
Double-J's whirlwind summer fling (Miami! Amsterdam! Toronto!) came to an end in August 2008 when Mayer, ever the gentleman, told reporters outside a gym that he dumped the former Friend. The two were on-again in October and even PDA-ed it up at the Oscars (in your face, Brad). A month later, it was the break-up, part 2.
Nicollette Sheridan and Michael Bolton
First got together: 1992; engaged in 2006
Number of splits: Two; most recently in 2008 
The long-haired blonde bombshell turned to the long-haired blonde rocker during her divorce from Harry Hamlin in 1992. They split in 1997 and rekindled their relationship in 2005, shortly after Sheridan called off her engagement to Swedish trainer Nicklas Soderblom. They got engaged in 2006, but never had any solid wedding plans in place.
Pamela Anderson and Tommy Lee
First got together: 1995; married 96 hours after meeting
Number of splits: Three; most recently in 2008
The Baywatch beauty wed Lee 96 hours after meeting him and thus began one of the most tumultuous and scandalous couplings ever. She accused him of domestic abuse and giving her Hepatitis C. And there was that whole sex tape thing. They divorced in 1998 and reconciled a year later before splitting again. Last year, Lee told Rolling Stone the duo was having another go at it and she was moving into his pad. By November, Anderson had moved out.
Pamela Anderson and Kid Rock
First got together: 2001; married 2006
Number of splits: Two; most recently in 2006
The couple got engaged in 2002 after a year of dating, but later split up. In 2006, the rocker and the Playmate finally exchanged vows in a July wedding aboard a yacht. Four months later, they were kaput.
Elizabeth Taylor and Richard Burton
First got together: 1963; married 1964-1974 and again 1975-1976
Number of splits: Two; most recently in 1976
What is this list without Liz and Dick? The two — who were each married to other people — started an affair during the filming of Cleopatra, which was très scandalous at the time. Poor Liz was even condemned by the Vatican for "erotic vagrancy." Burton made an honest woman out of the actress in 1964. They split in June 1974, remarried 16 months later and divorced again nine months later. During their relationship, they collaborated on many projects, including the aptly titled TV movie Divorce His — Divorce Hers.