I found out my marriage was over because of a little green dot that was supposed to be gray.

My mother had been failing for three weeks, and I had moved into her spare room to do the things daughters do when the order of the world inverts. I cut her food small. I learned the timing of her pills. I sat in the dark of an unfamiliar house listening for the catch in her breathing, the way I used to listen for my own children before they grew and left.

That night I couldn't sleep. It was past two, then it was past three, and the silence had a weight to it. I picked up my husband's old laptop, the one I'd grabbed by accident when I packed in a hurry, and I opened it just to have light on my face. His gaming network was still logged in. I don't game. I had only ever glanced at that world from across the living room, the headset on his head, the muttered strategy, the way he laughed at things I couldn't see.

His name sat at the top of the friends list. Online. A green dot, steady and bright, at three in the morning, two hundred miles from me.

I told myself he'd fallen asleep with it running. Magnus did that sometimes, left things humming. But there was a label under his name, the way these things announce what you're doing, and it said he was in a private voice lobby. And it named the game.

I knew that game. He'd shown it to me once, almost shyly, back when shy was a thing he still was with me. A cooperative game built for exactly two players, where you can't progress alone, where the whole point is that one of you holds a door while the other crosses, where you have to talk constantly or you both fall. He'd said, that's a couples' game, we should try it. We never did. There was always a reason. The kids, the dishes, the tiredness that had become the third person in our bed.

So who was holding the door for him at three in the morning?

The lobby showed a second name. A handle, cutesy, a flower and a number. I didn't recognize it, and then I did, because I'd heard him complain about her for a year. A woman from his office. The one he couldn't stand. The loud one, he'd called her. The one who didn't pull her weight, who he rolled his eyes about over dinner with a performance so consistent I never once thought to look behind it.

You don't perform indifference about someone who doesn't matter. I understand that now. The eye-roll was a decoy. He'd built it carefully, the way you build an alibi before you need it.

I sat there with the laptop heating my knees and I did the only thing I could think to do. I didn't call. I didn't burst in, because I wasn't there, because I was here, where the air smelled like medicine and my mother was dying one quiet breath at a time. I just watched the dot. For an hour. Two people, awake together in the dark, building something in a make-believe world while the real one slept.

I screenshotted everything. The timestamps. The lobby. The little flower icon. Then I closed the laptop and I lay down next to the window and I felt something I hadn't expected, which was not rage but a vast, clean loneliness. Because the thing I'd lost wasn't a body. He hadn't touched her, as far as I would ever know. What he'd given her was worse. He'd given her the nights. The talking. The thing two people do when they choose each other in the small hours, the attention I'd been begging for across a kitchen island for years while he stared at a screen and told me he was tired.

He'd never been too tired. He'd just been saving it.

I waited until my mother was gone, three days later, and buried, and I had nothing left to spend. Then I asked him, in our own kitchen, about a game I knew he'd say he never played anymore.

He lied so smoothly that I almost admired it. And when I turned the laptop around, the lie didn't even falter; it just changed shape, became smaller, became it's not what you think, became she's just a friend, became we only talk.

We only talk. As if talk had ever been the cheap thing. As if talk wasn't the whole marriage I thought I had.

I don't remember choosing to leave so much as realizing I already had, weeks before, in a dark room that wasn't mine, watching a green dot that should have been gray.

Some doors, once you stop holding them, just close. He'll have to learn to cross alone.