The social networking site, which connects old friends and allows users to make new ones online, is being blamed for an increasing number of marital breakdowns.
Divorce lawyers claim the explosion in the popularity of websites such as Facebook and Bebo is tempting to people to cheat on their partners.
Suspicious spouses have also used the websites to find evidence of flirting and even affairs which have led to divorce.
One law firm, which specialises in divorce, claimed almost one in five petitions they processed cited Facebook.
Mark Keenan, Managing Director of Divorce-Online said: "I had heard from my staff that there were a lot of people saying they had found out things about their partners on Facebook and I decided to see how prevalent it was I was really surprised to see 20 per cent of all the petitions containing references to Facebook.
"The most common reason seemed to be people having inappropriate sexual chats with people they were not supposed to."
Flirty emails and messages found on Facebook pages are increasingly being cited as evidence of unreasonable behaviour.
Computer firms have even cashed in by developing software allowing suspicious spouses to electronically spy on someone's online activities.
One 35-year-old woman even discovered her husband was divorcing her via Facebook. Conference organiser Emma Brady was distraught to read that her marriage was over when he updated his status on the site to read: "Neil Brady has ended his marriage to Emma Brady."
Last year a 28-year-old woman ended her marriage after discovering her husband had been having a virtual affair with someone in cyberspace he had never met.
Amy Taylor 28, split from David Pollard after discovering he was sleeping with an escort in the game Second Life, a virtual world where people reinvent themselves.
Around 14 million Britons are believed to regularly use social networking sites to communicate with old friends or make new ones.
The popularity of the Friends Reunited website several years ago was also blamed for a surge in divorces as bored husbands and wives used it to contact old flames and first loves.
The UK’s divorce rate has fallen in recent years, but two in five marriages are still failing according the latest statistics.
Mr Keenan believes that the general divorce rate will rocket in 2010 with the recession taking the blame.