Sometimes I sit my nieces down and treat them to tales of dating in the dark ages, before iPhones arrived to save teenkind. Poor nieces. Though they scuff their Uggs on the carpet and stare longingly at the door, I carry on.

When I was your age, I say, we had no access to boys. Those of us at mixed schools had a few limp options, and the rest relied on miracles: a hottie met by chance on holiday; a friend’s brother’s friend. There was no social media, no looking someone up, so unless you bagged your hottie sharpish he vanished. Boys surfaced like rare sea-mammals for single sightings before sinking back into the fathomless unknown.

No googling! Can you believe it, nieces? They can’t. They’re the Snapchat generation, born as the century turned. Life for them is a ceaseless stream of silent chatter, back and forth with pals, on apps. After puberty, they simply swipe through the catalogue of boykind, picking and choosing who to pursue.

To my inner teen, a 1990s girl, this sounds like paradise: boys on tap and privacy, too! No communal phone in a cupboard, no hot-eared parents idling outside the door. But there’s a problem in this paradise, something a 1990s teen could never have foreseen.

Though they’ve got everything we thought we wanted, the girls of the Snapchat era are still frustrated, more so than we ever were. I’ve questioned scores of them — little cousins, the daughters of friends — and most report that though boys are everywhere online, posing and posting, it’s near-impossible actually to meet one. The curious result of freedom is a generation of thwarted girls.

My generation, let’s call us the glandular fever generation, had a motto: snog first, talk later. So hard was it to get within range of a passable boy that when the chance came we leapt at it, face first. After the snog, perhaps the chat, and then a wait for a letter or call that would convert the snog into a boyfriend.

For generation Snapchat, the progression is different. First base these days is ‘friending’. This means adding some boy you’ve never met to a list of your online ‘friends’ and waiting for him to ‘friend’ you back. Next, the ‘liking’. The target boy might post a picture of his breakfast, or his stomach. You tap a button indicating that you like it, and wait for him to like a pic of yours in return. Third base is ‘talking’, meaning by text, on Snapchat. This has status in girl world, as in: ‘Guess what, I’m talking to Bob!’ ‘OMG she’s talking to Bob!’ But this, curiously, seems to be where 21st-century teen dating ends, in interminable, pointless conversation.

‘Hey, what’s up?’

‘Nothing much. What you doing?’

‘Not much. Homework.’

The talking without meeting goes on for months, and it’s insufferable. It’s like skipping the whole point of being 15 — the dates at Pizza Express, holding hands, the enamel bump of teeth — and going straight to the sexless back-and-forth of old age: ‘Nice day dear? Pleasant out, isn’t it?’

The girls want to meet, I know. They’re waiting, in the manner of girls throughout history, to be asked. It’s a sad but irreversible evolutionary fact that girls like to be chased, and boys most definitely do not. So it’s the boys who put the brakes on. But why? Don’t modern boys long to grapple with girls? Isn’t boy lust another immutable law? Well, I have a theory, a slightly depressing one.

Yes, teen boys are still hormone-crazed, but these days they’re also snowblind, paralysed by the extraordinary choice online. Whereas a girl is designed to fixate on a single love interest, boys are made differently. Confronted with the limitless sea of seductive-looking schoolgirls, your average boy is like a glutton in a cake shop, unable to pick one for fear another might be tastier.

You have to know a teenage girl and her social media habits to understand just how bewildering the cake-shop phenomenon might be to a boy. For a girl these days posting selfies on Instagram is compulsory: to ignore social media is social death. I have a friend whose pretty 17-year-old daughter gets dressed up and made up every evening, not to go out, but to spend time with the bathroom mirror, getting a perfectly angled selfie. Then she waits to count her likes. Her mother says the girl’s mood is linked quite precisely to the number of likes an evening’s look has received. No likes and she’s disconsolate, sometimes inconsolable. This is not abnormal.

Also normal is the come-hither pout — no selfie is complete without it. It’s a version of the face all women pull when let alone in lifts with mirrors, but taken to extremes. Some say the pout has its roots in the porn industry. I say it’s hardwired, and that close observers of bonobo behaviour will one day photograph gaggles of females all pushing their lips towards a tasty monkey male.

As Snapchat girls grow older, their posts get racier. Swimwear appears, and those peculiar naked stomach shots both sexes now enjoy. The aim is to gather ‘likes’ but there’s also a financial incentive. Should a girl attract enough followers online, she’ll be contacted, say my nieces, by clothing and make-up companies. They’ll pay her — in cash or goodies — to post pics wearing their gear with a sunny little comment referencing the swag: I love my #Converse. Summer means #RayBans.

Cash, peer-group kudos, the joy of being followed by thousands (who cares if they’re elderly perverts?) have pushed a generation of girls (though not my nieces) into a situation where they’re posting, for free, the sorts of semi-naked, come-hither shots a chap would pay for in the 1980s.

This then is what boy teens are presented with: an endless carousel of pouting hotties all lifting their T-shirts up on Instagram — not models but friends, sisters of friends, all available to text. So they’ll talk to girls in the virtual world, sometimes five at a time, because who’s to know who’s ‘talking’ to whom? But to go on an actual date? That would be to choose, to pick one and exclude the rest. That’s proving too hard for the Snapchat boys. I wonder, in a worried way, what will happen when they’re men.