Why do we grieve for dead celebrities?

It wasn't that I cared a whole lot about Princess Diana, or that I was particularly sad when she died. It was that I drove around London that night with my mum, through the crowds of red-eyed strangers in their jackets, and I smelled the flowers. Do you remember? They were piled up in the places she'd stayed like bonfires, higher than people, and the whole city was like a scented candle. The petrol stations had signs up saying they'd sold out of bouquets. And in that smog of roses I understood, suddenly, that each of these people, strangers to the woman, were honestly and deeply affected by her death. But in the same moment I felt sad for them, I felt sort of mortified, too. Were their lives so lacking in emotion that they found it here, on a pavement, on the very edge of their realities?

You see it today on Twitter, that first rush of celebrity RIPs – a mixture of shock, of competition, people rushing to report it first, and in between it all, the people who feel truly bruised by the loss. Not because they knew them, and not because they played a part in their lives – her song was not the first dance at their wedding, for instance; her face was not tattooed on their shin – but because something about her story reminded them of something about theirs. And she was a person, and so are they.

Sitting in the car park of a pick-your-own strawberry farm hours after Amy Winehouse's body has been found. Getting a text late at night about Lux Interior, about Philip Seymour Hoffman. Occasionally the bruisy feeling when you hear is due to their talent, due to them being cut off in their prime, but more often it's not. More often it's less tangible. A gulp. Brittany Murphy. Cory Monteith. We all have a celebrity death that hurts us and makes us feel something, even if, as we're feeling it, we're embarrassed for feeling it. As if our twice-removed cousin of pain might be insulting to the family of the deceased, as if we don't have a right. What are the rules to our reactions?

When L'Wren Scott died, I pored over the Samaritans guidelines on reporting suicide. They concentrate on the avoidance of words and details that will prompt readers to identify too closely with the deceased. You should not, for instance, speculate on their reasons for wanting to die. You should not describe the methods used. But even in the best, most sensitively reported stories, a certain level of identification occurs. The guidelines on reporting the way we feel upon hearing of the death of a person we know only from the party pages are far less clear.

Am I allowed to feel like this? That's what I keep wanting to ask. Am I allowed to want to talk about it, and read about it, and worry about her friends? And pause weeks later and feel doleful before realising why – a stranger died 3,000 miles away. To feel the imagined grief of their partner, distorted through paparazzi pictures, a reflection of a reflection.

The worry is that we're self-identifying, and making a stranger's death all about us. Projecting our own little concerns on to the blankness of a screen. The worry is that it reveals our own emptiness, our desperation for a feeling or thrown scrap of one. Or that we are so porous and sad that a stranger's experiences is enough to topple us. Either way, it's embarrassing. It's undignified. And yet it keeps on happening.

Are we practising? Using celebrities like dolls to play out the way we might feel when we lose the people we actually love? Is our obsession with the deaths of beautiful people, our compulsive consumption of stories about their final days, a way of preparing for real feelings, real loss? All those flowers in Kensington. All those RIPs.