Such is the extent of my sleep-deprivation these days that ideas need to percolate for some time before they become semi-coherent, let alone printable. But when I felt a familiar prickle of irritation not once but twice within just 10 minutes of browsing my usual news sites the other day, I was sure something needed to come out. The twin provocations were these:

1. an article entitled ‘What I learned from my daughter’s wedding‘ by the media consultant Tony Schwartz on The New York Times website. This piece concerned the ‘eureka!’ moment when Schwartz did a head count at his daughter’s nuptials and decided that if so many people turned up then Facebook must be a good thing after all.

Admittedly, reports of similar Damascene occurrences by formerly sceptical social media immigrants have become something of a sub-genre amongst the chatterati, but the way this one was cocooned by the soft-focus goodwill of a wedding in an effort to fend off any critique of its underlying point really got under my skin.

2. a Guardian Comment is Free post in which a regular applauded the columnist Simon Jenkins for his piece about the Prime Minister’s trip to Kazakhstan, signing her own remarks with an ‘x.’ Yes, that’s a kiss. To you and me and everyone else she’s never met.

In the spirit of transparency, I will blow my own whistle with the confession that I used to have a Facebook profile, but now I don’t. To be sure, my relationship with Facebook was always tenuous: accepting ‘friend’ requests from people I hadn’t seen in decades, followed by a volley of catch-up emails in which we mutually – albeit tacitly – agreed that our ‘connection’ looked less like a Venn diagram than the random contents of someone’s handbag spilled on a table. Or ignoring such requests altogether and being beset with mild guilt that felt like a low-grade but persistent stomach bug.

This tiresome ritual carried on until the day my sister Darya died of cancer. That same evening, I emailed my close friends and family to let them know. Some of them had never met Darya but they had held my hand through the roller-coaster of her illness, the final months of which ran parallel to my own twins pregnancy. They witnessed what I’d been through, and had surely developed a vivid picture of the suffering she had endured.

The day after her death, I received an email letting me know that a cousin I hadn’t seen in more than 30 years had written on my Facebook wall. ‘Oh, she’s heard about Darya,’ I thought. ‘It will be a condolence message.’ In fact it was a condolence message: my cousin had written ‘RIP’ on my wall. This is how I discovered that the depth of our connection was such that she didn’t actually know which sister had died, and which was grieving that death. She did not know who I was.

After my sister died, I had more to think about than my relationship with social media so it took a couple of months for me to shut down my profile, but I still recall the sense of relief that washed over me the day I called time on Facebook. Finally, I could stop trying to figure out what it was for, or how it could make my life ‘better’ in any meaningful sense.

Granted I was probably looking for proof, but this episode instantly vindicated my long-held sense that the so-called intimacy Facebook enabled was false, and that the currency of ‘friendship’ in which it traded was devalued by its overuse. I once asked my teenage nephew precisely what constitutes a ‘friend’ on Facebook. He laughed and said, ‘anyone you’ve ever met’ – but he was only half joking. I’m convinced that it’s this emotional sleight of hand, in which relationship boundaries become so blurred that we thoughtlessly indulge a baseless intimacy that prompts us to routinely sign correspondence – or comments on newspaper articles, as above – to virtual strangers with an ‘x’. (Although it’s slightly beside the point, I can’t help but note the irony of that intimate sign off on CiF, with its infamous vitriol.) It’s also reflected in the recent faddish American use of ‘reach out’ in lieu of ‘contact’, whereby mundane business enquiries are cocooned by the language of physical overture.

It might seem hypocritical to illustrate my distaste for Facebook through my sister’s death, surely as untouchable a context as Tony Schwartz’s daughter’s wedding. And he’s clearly right when he says ‘[Before Facebook] it wasn’t easy to keep up. Long-distance phone calls were expensive. It took a real investment of time to write a letter, put a stamp on it and drop it in a mailbox.’ But what troubles me about Facebook and some other social media is precisely the way the ease of contact Schwartz applauds invites the misplaced intimacy embodied by my cousin’s message.

I’m not suggesting that there is an inverse relationship between this ease and emotional connection, and I can’t remember the last time I sent someone a handwritten letter by post. I’ve lived away from my family and oldest friends for well over a decade now, and I’ve mostly kept in touch through email and phone. After all, the Internet didn’t just bring us Facebook; it brought us electronic ‘letters’ (aka email), and free phone calls courtesy of VOIP. These inventions eliminated some of the challenges Schwartz cites, while still requiring an investment in the one-to-one connection they help enable. What they didn’t do was hijack the very language of intimacy, turning ‘friend’ into a verb, while transforming the complex, ephemeral and profound bonds that constitute authentic friendship into a set of social media gestures.

Coincidentally, on the day I started writing this piece last week, the American researcher Brene Brown, whose 2010 TED talk on ‘the power of vulnerability’ went viral, was speaking at the RSA. I couldn’t attend but I listened to the lecture online, and was interested to hear Brown’s view of how we bare our souls on social media: ‘Vulnerability without boundaries is not vulnerability,’ she said. ‘Social media is great for communication – but connection happens between people, in person.’

To be fair, I’m sure a lot of people use Facebook for reasons that do enrich their lives. In fact, I recently discovered I couldn’t join a writers’ group because Facebook was the medium for discussion, and I admit that the problem did give me pause. But in the end I decided to stay on the wagon just so I could be clear who my friends are.