A year or so ago Caitriona* was going through a difficult separation. Her husband was causing problems by insisting he had no money -- but luckily Caitriona was able to prove this wasn't the case.
She logged on to his Facebook profile and on it found recent pictures of him thousands of miles from home standing in front of well-known landmarks smiling smugly at the camera. The shots of his costly holiday proved his claim of penury to be false and her husband's smug smile soon disappeared.
It's one of a growing number of instances where Facebook is having a major impact on marriages . . . and their demise.
Tabitha Wood, a Dublin-based barrister specialising in family and child care says: "The pictures in that case were a real two fingers up to the woman involved. From the point of view of someone representing a client in a case like that Facebook can be a really good resource to have, it really adds another string to your bow."
She adds: "My advice to anyone now going through a divorce or separation would be to be very careful about what you put on your profile because it will get looked at and could be used against you."
A new poll revealed that one in five UK solicitors and some 80% of lawyers across America now use the social network to firm up claims of a duplicitous or cheating spouse.
Photos that demonstrate false claims of penury are one thing, but increasingly people filing for separations and divorce are doing so after discovering their partner has been unfaithful via the medium of Facebook.
Dublin-based family law solicitor Roderick Tyrell says: "I've had clients coming in and telling me about logging on only to find their husband has listed himself as 'single' on his profile or that there have been booty shots up that they've known nothing about."
But as much as these findings may offend those involved, he warns that they won't necessarily affect a legal case.
"Clients take what they find very seriously, but there's not really that much legal weight given to it," he says.
"Judges don't tend to look into a couple's bedroom unless a person's behaviour is considered extreme. In the past there's been consideration given if a person is using more 'exotic' websites, but Facebook would still be seen to be fairly benign."
He adds: "And I think in most cases for the couples involved what they find on Facebook has confirmed their decision to go ahead with separating rather than instigate it."
But there are plenty who would disagree with that view or feel that the platform is 'benign'.
Just last week Wolverhampton Crown Court heard that wealthy American businessman Harold Landry (64) stabbed his 38-year-old British wife Lucy 23 times with a kitchen knife after learning she started an affair with an old school friend on Facebook.
And online there are thousands of stories on sites like Facebookcheating.com detailing the fallout from relationships destroyed when people have cheated via Facebook.
Sarah* (53) from Dublin says Facebook was a stepping stone in her husband's illicit online behaviour that ruined their marriage of five years.
She says: "My first tip-off was seeing that he'd listed himself as single on Facebook. That opened up a can of worms to a part of the internet I never knew existed.
"My marriage has been destroyed by my husband's addiction to internet porn. I honestly had no idea what was going on because he had all kinds of security tools fitted to our computer, it was a mess."
On Facebookcheating.com a man called Ray tells how his marriage was ended when he discovered his wife had started an online affair.
He writes: "One day when she was shopping, I turned on the laptop and guessed what the password was and there I saw it -- pictures of her kissing a guy, chats with him about how she missed him and how she thought the baby she was pregnant at the time was his.
"When she came home I showed her what I discovered, ended the marriage and kicked her out of the house. She's living with the guy now and we've sent DNA samples to the testing lab."
He adds: "I believe if she had not had the internet or Facebook her relationship with that guy would not have renewed, continued or whatever . . . but it was just too easy to maintain the contact."
Many maligned partners hold Facebook solely responsible for their relationships falling apart but Dublin-based psychologist Allison Keating from the bWell clinic thinks this attitude might be too much of a get-out- of-jail-free card.
"I don't know if Facebook can be held responsible for breaking down relationships but it's definitely adding complications to already complex relationships," she says. "Maybe it does make it easier to cheat but that doesn't make it right. There are sweetshops on every corner but that doesn't mean we have to eat in all of them.
'If someone is spending more time talking to someone online rather than to their partner who might be in the house with them then there are already problems in the relationship."
And whether you're the one that's suspicious that your partner is pursuing a secret life online or the one that's messaging an old high-school flame, it's important to realise that Facebook is not real.
"Everyone is always having a better life on Facebook, but that's because they get to decide what they do and do not reveal," says Allison, and relationship councillor Lisa O'Hara agrees.
She says: "You might be talking away to someone online and feel like you're getting on really well but it's not real. The barrier of the screen means people can be as honest or as dishonest as they want. It will never take the place of face-to-face communication and anyone who is spending an inordinate amount of time online is trying to avoid something in their real life."
*Names have been changed