You know the thing about completely fannying your life away on an alternative, online universe like Second Life? A place where you create an “avatar” and then wander around, interacting with other “avatars” from around the world? It’s all quite reasonable, really.

I mean, here’s Carolyn. Once she was a bored US mother-of-three, living in a flyover state, and so depressed she “cried whilst she did the laundry”. Now, however, thanks to Second Life, she’s got options on being a black-eyed sex-Goth, with tits like the Millennium Dome. She can spend all day eating tiramisu without putting on a pound, then open up her gigantic wings, fly off to the Sex Forest, and have sex with men who look like Flea from Red Hot Chili Peppers. And all for $9.95 a month! In these inflationary times! What a result.

Let’s face it – very miserable people do much worse. Much, much worse. She could have ended up a skanky crack whore. An alcoholic gambler. A Scientologist. Even something more low-key and humdrum, like a codeine habit, would have cost her a tenner a day – and eventually left her with terrible constipation.

In comparison, on Second Life, Carolyn’s going to the toilet regularly. She’s even able to offer rudimentary parenting to her own three children. After all, there’s no reason why the kids can’t just sit quietly on the bed, eating crisps, while their mother smokes a fag and “rezs” a butterfly on Svarga. For the next ten years.

Bearing in mind that she seems to be a doomed, feckless idiot with all the mothering instinct of a chicken-wire crate, it might well be that getting into Second Life was the best stupid decision Carolyn ever made.

Alas, where it gets complicated is that Carolyn has “fallen in love” with someone she met on Second Life – and her affair is the subject of Virtual Adultery and Cyberspace Love.

While Carolyn’s children merely stare at her with baleful, unloved eyes, her husband, Eddie, is actively racked off about her cyber cuckolding. And not too surprisingly, really, given that he’s out there all day busting his balls servicing air conditioning units, only for his wife to spend his hard-earned dollars repeatedly clicking on someone else’s genital icon and typing “ZOMG!!1!1”.

“I love her like she loves him,” Eddie says, sitting, sad, crumpled and slightly overweight, in their shabby-looking kitchen.

But what hope has worn, real, meat-world Eddie got against “Len”? Second Life “Len”? Completely imaginary “Len”? Len is 6ft 6in of pixellated muscle and Goth piercings. He even has a revolutionary view of men’s tailoring.

“I don’t think I’ve ever worn a top,” he “says”, “standing” in front of a 100ft Second Life waterfall, “just trousers, and weapons.” He neglected to mention – perhaps from modesty – that he was also wearing a scarf made of a live snake.

Carolyn, Len and his hissing accessories spend up to eight hours a day together online. They go on “dates”, and have cyber sex. I’m sure, when most of us say “cyber sex”, we all think of something polymorphically perverse. Maybe sudden explosions of silver seahorses from a pixellated crotch.

In reality, Carolyn and Len just sit on top of each other, fully clothed, and fidget around a bit. Given how unsatisfying and adolescent it is, it’s more like “cider sex” than “cyber sex”.

However, shagging that would make any onlooker laugh like a drain seems to be of no comfort to Carolyn’s husband. He, like us, was left asking some big questions. What is the nature of fidelity? Can you be unfaithful with someone you’ve neither met nor touched? And what are the washing instructions on the snake?

Of course, in the end, Len and Carolyn met in real life. Carolyn flew 7,000 miles to the UK, and finally eyeballed Len: aka Lee, a rather faded fortysomething with sad eyes. In an attempt to mirror the magical Elysian valleys of their Second Life, Lee and Carolyn took to Primrose Hill, North London, on a grey afternoon, and had one of history’s most awkward and unatmospheric picnics. They ate Doritos while avoiding eye-contact, spoke at the speed of one-fingered typing, and clearly wished for the benefit of an exclamation mark and an “off” button. The relief when she flew home was tangible.

The lifelong connecting of two hearts, the show made clear, is just as complex and fraught on Second Life as it is in real life. But it’s clearly much easier to sell a live snake as a tie online.

Wonderland: Virtual Adultery and Cyberspace Love, Wed, BBC Two, 9.50pm (Scotland: Tues, 9.50pm)

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