ON YOUR RADAR: The Biggest Breakups Of The Year

By Debbie Emery - RadarOnline.com Reporter

Hollywood will have its fair share of lonely hearts this Christmas after countless couples went their separate ways during 2011. RadarOnline.com reveals the celebrities who have gone through bad breakups and are in need of a helping hand from Cupid and his arrow before Valentine's Day comes around.

CBS Evening News anchor Katie Couric doesn't often find her name in the tabloids but her split from longtime boyfriend Brooks Perlin after five years earlier in December took everyone by surprise. Couric, 54, reportedly initiated the breakup with her 37-year-old beau, and is already looking for a new love!

Catching boy toy husband Ashton Kutcher cheating for the second time in just over a year was too much even for Demi Moore! The Striptease star announced she was filing for divorce from the Two And A Half Men actor after details of his drunken hook up in San Diego with Sara Leal emerged in October.

With two adorable twins and a string of hit songs under both their belts, Jennifer Lopez and Marc Anthony's bombshell breakup in July rocked the music world. The couple had been together for seven years but that didn't stop the 42-year-old Jenny From The Block singer quickly moving on to a much younger man by stepping out with 24-year-old back-up singer, Casper Smart.

Ali Fedotowsky didn't help the success record of The Bachelor romances when she announced in November that she and fiancé Roberto Martinez had split up after a year. Within a day of the breakup, The Bachelorette star turned Fox News reporter had already returned her 3-carat asscher-cut diamond engagement ring to the jeweler Neil Lane, RadarOnline.com exclusively revealed.

Possibly one of the least shocking splits of the year was 85-year-old Playboy founder Hugh Hefner and his busty blonde fiancée Crystal Harris who announced they were parting ways just days before their June wedding amid rumors that she was dating Dr. Phil's son, Jordan McGraw. The 24-year-old Playboy playmate quickly packed her bags and moved out of the Mansion, but instead of giving back her huge 3.39 carat diamond ring she put it up for auction!

Arnold Schwarzenegger and Maria Shriver's breakup after 25 years of marriage became one of the biggest stories of the year in every way when a joint investigation by Star magazine and RadarOnline.com revealed in May that he had fathered a love child, who is now 14, with his housekeeper, Mildred Baena. Maria filed for divorce on July 1, and the former California governor, who is worth roughly around $500-750 million dollars, reportedly is agreeing to a generous settlement.

Rumors that beautiful couple Leonardo DiCaprio and Bar Refaeli were on the outs began circulating in May when the Israeli supermodel walked the red carpet alone at the prestigious Met Gala in New York City. It didn't take either side long to bounce back from their on-again-off-again five year fling as Bar was soon linked to David Fischer, while Leo dated Gossip Girl star Blake Lively until October.

Many thought that New York Yankees star Derek Jeter and Minka Kelly's relationship was a home run to the altar but the couple struck out in August and called it quits. 2011 didn't get any better for the former Friday Night Light's star when her new project, Charlie's Angels, became the second network show of the year to be canceled.

They say once a cheater, always a cheater - and Jesse James certainly supports the theory! After his marriage to Sandra Bullock exploded, the Monster Garage star got engaged to tattoo artist Kat Von D. Despite sharing a passion for getting inked, the couple split up in a similar spectacular fashion when Kat announced on Facebook that he had been cheating on her too. In a lengthy Facebook blog titled “Thank You, Jesse James,"  Von D revealed that her relationship with Jesse was “toxic” and that she “encountered” the 19th woman he’d cheated on her with during their relationship.

And, save some sympathy for some other notable romances that suffered a sad demise during 2011!

British actress Elizabeth Hurley and Arun Nayar ended their three-year marriage after her rumored affair with a cricket star; Olivia Wilde and childhood sweetheart hubby, Tao Rusapoli, parted ways after she admitted that she had married too young and notorious lady's man Alex Rodriguez left another broken heart in his wake when he and actress Cameron Diaz split.

You can check out all the biggest break ups of 2011, here on RadarOnline.com.