Last week at a conference dinner, I walked in with too many good options. A few tables I knew, a few I didn't, and that small hesitation when every choice feels fine but none jumps out. I was wandering a little longer than I realized when Andrew noticed, caught my eye, and waved me over.

It was that kind of room. The kind where the conversation goes deep fast, where someone asks where your energy is going these days and before long you're talking about the things that actually matter.

I told Andrew about the book, and he leaned in. And then he said something I've been thinking about since.

He told me he'd lost a close friend recently, and in the months that followed, he'd noticed himself doing something he didn't entirely understand. He was walling off. He was apprehensive about forming new friendships. About investing again.

I scribbled three lines in my notes app at the table, and then I sat with it for the rest of the night.

I haven't lost a close friend. Not yet. I've been spared that, so far, in a way that I know isn't going to last forever.

But the people closest to me have. My wife has buried a friend. My brother has too. And a few months ago, the co-founder of my last business had a heart attack that almost killed him. The kind where you find out after the fact, and you spend the next few hours trying to remember the last conversation you had with him.

I'm in my forties. The runway is shorter than I've been pretending it is, and Andrew's words landed because they weren't a memory for me. They were a forecast.

Most of us, if we're honest, have not really sat with what adult friendship actually costs.

Childhood friendship doesn't ask this of you. You weren't aware of mortality at twelve. You weren't thinking about who would be at whose funeral, or whose call you'd answer one day with your stomach dropping. The friendships you made then felt infinite because, in a way, they were. The future was so far out you couldn't see the edges, and the people you loved felt like fixtures rather than gifts that would eventually be returned.

Adult friendship is different. Every real connection you build now is, at some level, a future loss you're agreeing to. The grief is in the contract, even if nobody tells you that when you sign it.

When Andrew pulled back, he was paying the cost.

Sit with that for a second. The instinct to wall off after losing someone is the heart doing exactly what it was built to do, which is to protect you from doing something that hurt that badly ever again.

It's rational. It's protective. It might even be wise, depending on how you measure these things.

It's also a mechanism, I suspect, by which the back half of adult life gets lonelier and lonelier without anyone ever consciously choosing it. You lose someone, and you flinch. You stop reaching out, dial it back a little, or perhaps you keep things a little more surface than you used to. None of it feels like much in the moment. And one day you look up and the circle is smaller than you remember it ever being, and you're not entirely sure how to get it back.

But the flinch itself is the proof.

The fact that we pull back from forming new friendships after losing one is evidence of how much they were worth in the first place. The grief and the value are the same thing, measured from different sides. We don't flinch from things that don't matter.

That should mean something. Because the thing we're tempted to retreat from, the thing that hurts so much we'd rather just not risk it again, is the same thing almost everything we know about a meaningful life points back to.

It's the people. It was always the people.

So what do we do with that?

I don't have a clean answer. I haven't had to face this yet. I'm writing this from the perspective of someone who watched it land on someone else and started to feel the weight of it for the first time.

But here's the question I've been sitting with since that dinner.

If you lost one of your closest friends tomorrow, what would you do?

Would you keep investing? Would you reach for new people, knowing it might happen again? Or would you find yourself doing what Andrew described, quietly, almost without noticing, walling off?

Most of us have never asked ourselves that question. It’s not the kind of thing we want to think about.

I think that’s a mistake. Not because dwelling on loss makes us better, but because the reflexes we'll have when it happens are the reflexes we're building right now. In how we show up. In how willing we are to be inconvenienced by the people we love. In whether we keep reaching, even on the days when reaching feels like more than we have in us.

I don't know exactly what I'd do, if I'm being honest. I know what I want to do. I know what kind of friend I want to be on the other side of a loss I haven't lived through yet. And I know that the work of becoming that person doesn’t start when the call comes. It starts now, in the small choices nobody’s watching.

The friendships I have today are the ones I'll someday have to lose.

That's not a reason to invest less.

It might be the reason that matters most.