I’m 35 and I just realized the friends I had at 25 didn’t drift because anyone did anything wrong — research suggests social networks often peak in the late twenties and quietly shrink after

A few months ago on the golf course, something hit me that I haven’t been able to shake.

I was out playing a few holes with a friend, and we got onto the topic of who we’re still in touch with from our twenties. Between us, we counted maybe four people. Four. From a circle that, ten years ago, must have felt closer to thirty.

I drove home thinking I’d been a bad friend. That maybe I’d let people slip. That moving from away from Ireland had quietly cost me more than I realized. 

But after I started looking into the research, my view shifted. The friends I had at 25 didn’t drift because anyone did anything wrong. It turns out, social networks tend to peak in the late twenties and quietly shrink for decades after, but nobody warns you that’s the schedule.

Twenty-five is the high water mark

In 2016, a team of researchers led by Kunal Bhattacharya pulled off something most studies can’t. They got hold of mobile phone records of 3.2 million people and what they found was striking. The number of people we regularly stay in touch with peaks right around age 25. After that, it drops steadily until our mid-forties. Then it plateaus for a decade or so before falling again.

The researchers also noted something interesting about why. Younger people, they wrote, are “socially promiscuous.”

We meet a lot of people, we say yes to a lot of things, we’re still figuring out who fits. As we get older, we focus our limited social energy on a smaller, tighter group. Family. A few core friends. The people we actually count on.

That’s not a bug. It’s how the system tends to run.

It’s not that anyone did anything wrong

Here’s what I think the real driver is. Friendships need time, and adult life systematically takes that time away.

Research by University of Kansas professor Jeffrey Hall suggests it takes around 40 to 60 hours together to form a casual friendship, 80 to 100 hours to actually become friends, and more than 200 hours to become close.

Picture those numbers against your average week at 35 or 45 or 55. You’ve got a job that probably eats fifty hours including the commute. A partner. Maybe kids. A house that needs maintaining. Parents who need looking in on. Whatever exercise or hobby keeps you sane.

By the time you’ve covered all of that, the casual hangouts that used to top up your friendships at 25 just aren’t there anymore. Nobody’s doing anything wrong. The maths has just changed.

When I think back to my twenties in Dublin, I had time I didn’t even know was time. Pints after work. A whole Saturday with nothing on. A spontaneous trip to Galway because someone suggested it on a Thursday. That’s the soil friendships grow in, and most of us run out of it without noticing.

The decline is so gradual that you can lose half your circle before you stop and notice it’s happening.

What I’m doing about it now

Knowing all this has made me less guilty and more practical.

I’ve stopped worrying about the friends who drifted because of geography or life stage. They didn’t disappear. The conditions just changed, and that’s okay. I can still send a voice note to a guy I haven’t seen in five years and pick up like nothing happened.

But I’ve also gotten more deliberate about the friends I do see regularly. I block out time for them on the calendar like it’s a meeting. I show up to things I’d otherwise skip. I’d rather see the same three people once a month than try to keep twenty plates spinning badly.

I’ve also gotten better at the small maintenance stuff. A voice note instead of a text. A photo from the golf course with no agenda attached. Little things that don’t feel like effort but add up over a year.

The bottom line

If you’re somewhere in your thirties and you’ve been quietly wondering why your social circle feels smaller than it used to, you’re not failing. You’re following a pattern that the data says is almost universal.

The friends from your twenties may not have drifted because anyone messed up. They may have drifted because the time and proximity that made those friendships easy quietly disappeared. 

Knowing the schedule helps. You stop blaming yourself, and you start being smarter about where the hours go.

If you’ve been feeling genuinely isolated for a long stretch — the calendar isn’t the only answer. Persistent loneliness can be a sign of something worth talking through with a friend who’ll really listen, a GP, or a therapist. The schedule isn’t all of it.