It is a depiction of Valentine’s Day highly suited to New York, a city full of encounters, personal ambition, fleeting happiness and complicated rituals of love. What is Sex and the City, New York’s most recent myth of itself, if not a kind of epic, doubtful search for fulfilment in a community which seems to have everything, if not quite the right thing for you?

So for lots of people here, Valentine’s Day means anxiety, a day of questions and appraisal: is this person really the answer? Why does no one love me? Even the shops don’t seem to know what to make of it and advertise confused Valentine’s Day sales. My local Kmart, for instance, is offering a 70 per cent discount on its supermarket jewellery near a sign which reads “Precious Love.”

To take a look at New York’s complex heart, I went to the MissedConnections section of Craigslist, the city’s all purpose listing website. Missed connections is where (mainly young) New Yorkers post their fleeting encounters. It is one of the most popular sections of the website and a kind of crystallization of our most haphazard hopes for love, of a city of halves endlessly chasing each other.

At first it reads like a straightforward list of shots in the dark: “I saw you on the bus this morning, we pulled up to your stop and you smiled and came aboard.” “I had the dark spikey hair and the blue/orange jacket…” “You were tall, skinny, pale, had messy brown hair, a plaid flannel shirt and jeans. I hope you saw me looking at you…”

Simon Brown, for instance, was taking the subway to work last Thursday and he couldn’t take his eyes off a girl dressed head to toe in denim. Simon, who is 31 and writes for a small magazine, was listening to headphones but he felt something pass between them. He put his message up a few hours later. Simon posts messages up every couple of months, “when someone sticks in my head and I feel that there was something shared,” he explained later to me, in an email.

But a closer reading of “Missed Connections” shows – as in every game of love – that there is more going on than meets the eye. There are plenty of fictional postings for instance: people using events that never happened to put out pleasing, rakish descriptions of themselves in the hope of provoking a genuine connection from the silent crowd that trawls the website every day.

And there are more devious ploys than that. A woman called Laura told me that her entry, about seeing someone on the A-train (“I saw that smile and thought ... wouldn’t it be nice to just ... stay in?”) was part of a game she plays with a friend. They both post messages and try and spot each other’s entry in the crowd of people exchanging glances. Not that fiction prevents people from replying and claiming a connection. Laura received five responses about her encounter on the A-train. One of them, from a man called Edgar, was especially sincere: “I'm about 5'10, look in the glass section of the train door, and catch your eye ... Will I ever see U?”

A more honest, perhaps, but equally creative tactic is to use the site to confront and publicly bemoan the lack of romantic, unrequited encounters in your life. Last Thursday morning, Jasika Nicole, who is 22 and originally from Alabama, was temping away in a blank cubicle and decided to head off her missed connection before it even happened: “I suppose temping wouldn’t be so bad if the possibility of meeting some cute, quirky and interesting guy at the office were feasible, but honestly ... ,” complained Jasika, who seems to have built her life in New York around things she found on Craigslist. Jasika emailed me, from her temping boredom, to explain that she had discovered jobs and two boyfriends on the site, as well as a shampoo-testing gig that made her hair fall out.

But, like the world on Valentine’s Day, the missed connections list is not just an odd mixture of hopeless romantics and worldly, life-hardened cynics, there are some, like most of us, who are foolish and detached at the same time.

Sabrina Ellis, for instance, a student at New York University, decided last week to write an essay about Craigslist, and whether its virtual world of glances was the same as the subway and jostled crowds where we have our more substantial encounters. But as she was putting together her cool analysis, Sabrina found herself staring at a guy in the bookshop.

“If I really had the guts I could have talked to him in the bookstore… the more I watched him walking back and forth across the store the more I thought he’d be interesting to talk to,” she said afterwards.

For Sabrina, who recently moved to New York from Texas, the city’s mixture of endless crowds and places, like Craigslist, to record your sightings “makes going on the subway almost like a romantic comedy”. But like everyone in New York who has joined the huge, love-seeking crowds – virtual and real – it hasn’t taken Sabrina long to come across the hard question that never goes away. “I just wonder if people ever find who they’re looking for,” she asked. “It seems so big.”

Slices of New York