Donna writes a song to David. It's a sad song. She records it on her laptop: her guitar strings, her voice, trembling. Then she uploads her song to YouTube and, one month later, five thousand people have heard it, and cried along with her. This is the age of sharing; whatever you feel, you can record it. You can find others to feel it with you. And then that feeling takes on its own life. It no longer belongs to you.

She tries to forget David. Half a year later she feels ready to remove the song, but when she visits YouTube and types in her title she finds a new version. Three pre-teenage Japanese girls in knee-high white socks and yellow blazers are singing the chorus, over and over, in cutesy voices while psychedelic bubbles float across the screen.

Donna's emotion has been hijacked.

She shuts her laptop and wanders downstairs to the kitchen. While she washes up she finds herself singing her words in a silly little voice. She can no longer remember how her original version went.

The Japanese song goes viral. It's on the radio, on the television, the world is singing it. The virus is an encapsulation of Donna's inspiration; David, the world sings, in breathless piping voices, David, don't you want me now? Want me now? Want me now? The words of her broken heart, made meaningless, made vapid and clever, all at the same time. How post-ironic you are, to mock this melancholia.

Donna opens her study window, and throws her laptop into the garden.

She walks down the stairs, makes herself a coffee, and sits down at the dining table, looking through her window to her front lawn, where the smashed pieces of plastic lie. The afternoon turns into the evening, and she takes the bus across town, to David's flat. He comes to the door, still in his suit, sighs, and runs his hand over his face.

"Hi," he says, "Listen, I've only just got in from work. You should have mailed or something."

"I couldn't. My laptop's broken."

"What's up with it?" She sees his relief at the idea that he is being called upon as a handyman, not a lover. "Do you want me to take a look at it?"

"It's beyond that. Can I come in?"

"Actually," he says, "Let's go out."

He takes her to a rich, quiet bar on the corner, with gleaming mirrors on all the walls and a real fire. She sits close to the flames, on an upholstered stool, and puts her mobile phone on the table in front of her. She presses a few buttons, and then waits for David to buy the drinks. She has her first line ready to sing.

He returns, and puts down two bottles of Czech lager, small enough to betray his hope of making this a short conversation.

"Donna, you can't keep doing this," he says, before he sits down.

"David, don't you want me now?" she sings. "Want me now?"

"Oh God, that bloody song, it's everywhere. Look, seriously, you need to let go. I do care, I'll always care, and I want to make sure you're happy. But you can't be happy with me. We make each other miserable."

"I wrote it," says Donna.

"Wrote what?"

"That song. David. Want me now. I wrote it for you, and put it on the internet."

"Are you serious?"

"And it got copied. It's not right any more. It meant something, my way. They cut all the verses and made it... happy. But it's meant to make you understand how much you hurt me. Listen." She sings it again, the whole thing, the verses about him packing his clothes and pretending it's for her own good and using tired old phrases instead of telling the truth. After the first verse he turns his head and stares into the fire, and she feels gratified that she has embarrassed him enough to make him look away.

She finishes the song. "I'm done," she says. "Do you understand now?"

He meets her eyes. He says, "Don't you get it? I always understood. You're loving this, aren't you? You love every drop of pain, every moment of unhappiness. It gives you something to sing about. It's never occurred to you to sing something cheerful, has it? You've never once let me make you feel good. I broke up with you so that you'd have a chance to find someone who can show you that life isn't all about sad songs."

"No," she says. "You broke up with me because you wanted a girlfriend who is prepared to pretend that life isn't shit. Who doesn't write songs about how much modern life hurts."

"Modern life doesn't hurt! Look at it! This is modern life. We're warm, and fed. We had each other. We'll meet new people." He gestures at the fire, at the gleaming mirrors of the pub, at the beers on the table. "Can't you let this stuff please you?"

Donna shakes her head. "David, you've become so shallow. I thought I could make you see. But you want television and ready meals and nights at the pub more than you want me, don't you?"

"Ah, now there you're wrong," he says. "Because I don't want you at all any more."

She looks at her untouched beer, and thinks of her broken laptop, lying on the lawn in pieces.

"Look, it's been a really long day," he says. "Let's just... cool off."

"Bye, David." She stands up and slips her phone into her pocket.

"You shouldn't have just turned up. You could have texted. I'd have told you it was a bad night. We've got a new contract on at work, it's manic, I'm going back to work on it at home now, I'll be up until midnight. Will you be okay getting back to yours?"

"I needed to have a face to face conversation. Otherwise it wouldn't have worked."

"What wouldn't have worked?"

Donna leaves. She thinks maybe he calls her name as she walks out, but she's not sure.

The next day she buys a new laptop, takes it home, and opens it. It's clean and empty. She uploads the conversation she had with David from her phone, and puts it on YouTube with a caption that reads

WORDS. RECORDED.

Once that's done she feels better. A new song has started to grow inside her head. She picks up her guitar and starts to strum.

People hear the words, recorded. They come across them randomly, or by tracing the writer of the song to David. One listener is moved by them. He annotates them, and adds a little detail. He makes a story of them, and puts that story online, on his blog.

You read this story, and you think you can appreciate the truth of how the world changes. Boyfriends and girlfriends stay together until they realise they have changed. They no longer speak the same language; in fact, they never did.

But the truth is this - you do not change. Only the words change, when you record them. Words: recorded, splayed, primped and perfected, tell you that the moral of the story is this. When the truth is that there is no moral at all.