Why should the Brangelina split matter?

Word that Brad Pitt and Angelina Jolie were calling it quits after 12 years as a couple sent shockwaves around the world and social media sites into a frenzy this week. Yet celebrity marriages come and go, so why, then, are we so interested in this one?

Outside the metal gates that mark the entrance to the couple's compound sat a lone TV cameraman, a freelancer for one of the tabloid TV shows.

Two days had passed since one of the most glamorous couples in the world had announced they were bringing their high-profile union to an end. At first glance you could be forgiven for thinking the news media had already moved on to the next story.

"Oh no, it's not just me here, they're everywhere," said the cameraman, reaching into his backpack to retrieve a ham and cheese sandwich.

Nodding in the direction of the dozen or so cars lining both sides of the streets with their engines running, he summed up their presence in a word: "paparazzi".

Brad and Angelina have rarely been out of the spotlight.

Whether it was falling in love on the set of a film, touring orphanages and taking issue with human rights, or cultivating a family of children with unusual names, their exploits always seemed so much more colourful than those of their fellow movie stars.

Today's film stars inhabit a world of social media and paparazzi photographers

In an era in which gossip has become more about pictures than words, it was inevitable, then, that the paparazzi were never far away.

But if their marriage was a media circus, it may turn out to be nothing compared to their divorce.

Who was to blame? What happens next? Where do they go from here? The questions go on and on and, amid the cacophony, there are lawyers to be consulted, possessions moved, court dates set and honoured. It will pay to keep the engine running, because you never know when you might have to give chase.

What is it, then, that makes us care so much about people we have never met and who don't even know we exist?

Turn left out of that sprawling compound and at the end of the street you come across Bob's dry cleaning shop. Above the counter - amid the faded images of a string of lesser celebrities - are pictures of Brad Pitt and Angelina Jolie.

A patron of Bob's myself, I asked about those pictures on my first visit. It turned out that he knew a lot more about their laundry than about the couple themselves, having never met them, because they always sent someone else to collect their clothes.

Bob could be forgiven for hinting occasionally at a level of intimacy that transcends that of the delicates and non-colourfast cottons - just as I am now telling everyone I meet that the man who puts the starch in Brad Pitt's underpants also takes care of my own.

Golden Age power couple: Lauren Bacall and Humphrey Bogart

Because at the end of the day, that's the thing about these people - we feel like we know them even though we don't.

While at one level it may almost seem as though they inhabit a different galaxy to you and me, we have nonetheless reached a point - thanks to social media - where nobody seems so very far out of reach.

Rivalled only by the power couples of a bygone age - think Bogart and Bacall, Tracy and Hepburn, Burton and Taylor - Brad and Angelina have proved better than most at keeping their distance, allowing just enough of a glimpse through the keyhole of their lives to cultivate our curiosity and leave us hankering for more. Always anxious for a fairy tale, we lapped it up eagerly.

Until, that is, the fairy tale turned sour and suddenly their pain became our own. Vogue magazine called it "the day love died" and others spoke of how - having served as a cushion to the drudgery of daily life - the unravelling of this glamorous partnership had left them feeling disorientated and disillusioned.

At the end of the day we care - not just because Brad and Angelina gave us something to believe in, but because their failure could trigger doubts in ourselves.

If people as gifted as these cannot make it - so the thinking goes - then what hope for romance? And what hope for the rest of us?