It was a Friday night in New York City, and for once, we, the girls, had pulled it off: A six-person table at The Odeon, 8 p.m. sharp, reserved a week in advance like proper adults. We were going to order martinis and steak frites and talk about everything—jobs, exes, celebrity gossip, the usual liturgy.

Two espresso martinis in, someone was deep into a story about a finance guy who wept after sex. We were howling when, suddenly, a voice chimed in. It was deeper than it should’ve been.

“I’d argue it’s a good sign that he’s in touch with his emotions.”

We turned.

It was Brad.

Sara’s boyfriend.

Apparently, now a regular at our dinners.

An hour earlier, Sara had texted: “Hey! Brad’s work dinner got canceled last-minute. Do you mind if he tags along?”

The thing is, Brad didn’t just tag along. Brad inserted himself. Into plans, into moods, into the background of my iPhone camera roll. He had shown up to brunches (plural), walks in the park, a movie night, and a “quick drink” that turned into oysters and a monologue about his literary magazine. Two weeks earlier, he joined me and Sara for a pedicure.

He became a fixture in what had once been women-only terrain. Our conversations, once unfiltered and electric, now had to be pre-chewed for male digestion.

I remember muttering, more sharply than I meant to:

Leave. Him. At. Home.

I didn’t hate Brad. In fact, I thought he was a great boyfriend to my friend. But the reality is that I never chose him. None of us did, any more than a tenant gets to choose their neighbors.

The truth is, friend groups are tightly knit and curated ecosystems that can quickly go haywire if even one of their members is codependent on a significant other. Co-dependence can masquerade as closeness, slowly displacing everything that once belonged like a foreign weed introduced into a native garden. Unfortunately, I know all about the slow, almost imperceptible shift toward someone else’s center of gravity from personal experience.

You know the girls who start dressing like their boyfriend’s dream version of a woman? Who adopt his music taste and his worldview like they’re auditioning for a role? That was me. I once found myself riding down the side of a Brooklyn freeway in mini shorts and a bikini top, on the back of a motorcycle, thinking this must be love. (Now, I just thank God I still have skin left.)