Popular social networking website Facebook is being blamed for a growing number of divorces as bored and lovesick middle-aged couples hook up with their ex-lovers or childhood sweethearts.

In Britain, divorce lawyers claim the popularity of social networking websites are tempting people to cheat on their partners, with firm Divorce-Online blaming Facebook for almost one in five of the petitions last year, the Telegraph reported.

Relationship Services NZ national practice manager Cary Hayward said although he did not have any local Facebook divorce figures he believed the problem was not as bad in New Zealand.

But he conceded the internet's impact was an increasing issue that was being discussed more often in the organisation's counselling rooms.

"I wouldn't say it's causing one in five marriages to break up but it is causing concern ... there is definitely a thing about technology accessibility and anonymity in the privacy of people's homes," he said.

"These days people have much more unmediated access to relationships and content online. It creates new opportunities for communication and it's something that more couples have anxiety about."

Statistics NZ figures show about a third of people who married in 1983 had divorced before their silver wedding anniversary. The median age at divorce in 2008 was 44. 5 years for men and 41.9 years for women.

Mr Hayward said relationships often had issues between five and seven years "because of some conflict in the relationship" or around 12 to 14 years, when people had become habituated to each other and tended to withdraw emotionally.

"It's a danger zone where if people don't feel like they have that level of emotional contact or emotional satisfaction they are more likely to be going online and looking for other kinds of contact and emotional stimulation."

Auckland psychotherapist Kyle MacDonald said the number of divorces caused by Facebook was surprisingly high. He said people should not blame the technology.

"I always find it funny that people blame the technology ... obviously there was a problem in the relationship to start with."

Private investigator Kerrie Pihema, whose Wellington firm investigates infidelity cases, was also sceptical that the medium was solely responsible for relationship break-ups, but her investigations found a clear correlation between previous unfaithful behaviour in a relationship and behaviour such as flirting online.

In Australia, online behaviour was starting to cause friction in households, Australian Family Relationships Clearinghouse manager Elly Robinson said

"People will come in [for counselling] where one partner may deny their online behaviour has been any sort of problem, but the issue is ... if it's upsetting one of those people in the relationship, it's a problem," she said.

"Relationships develop more quickly online because inhibitions are lowered, it's easy to exchange information, people are online 24/7, there's an [endless] amount of people you can link up with who are there for the same reason ... it's a bit of a fantasy world."

- additional reporting: agencies

By James Ihaka | Email James