A few days before a first dinner, I send the same message to everyone. It's short. It says: I'd like this to grow into more, in time; I'm assuming our upcoming dinner is just dinner but whatever happens after is entirely up to you. Everyone reads it; what they do next is the data.

This week I sent it to four women with dinners in the same fortnight. Here's what came back.

Saori: the self-upgrade Nineteen, tiny, a year on the app with a reply rate of four per cent, which means she's ignored roughly four hundred men and answered me.

Coffee was the Kurumi pattern: nervous for a quarter of an hour, hands round the cup, then she seemed to relax as the switch flipped. She was dressed somewhat conservatively, a knee-length black skirt and white blouse, with long wavy black hair. She was warm and quick and funny about the supermarket she works shifts at between economics lectures, and karaoke, and Mrs Green Apple. I sent the framing message with the dinner-only option made explicit, because she's nineteen and I wanted her to have the exit clearly marked.

She wrote back inside half an hour, and she'd removed the exit. Dinner, yes, and she'd like to go on somewhere after, if that was all right. She suggested the hotel before I'd said the word.

Maru: next time

Nineteen, a student, the profile everyone writes – looking for someone I can see long term, at an easy pace – and a thread that had been pleasant and unremarkable. She looked similar to Saori, long black hair, slim and petite in a black and white long checkered maxi skirt. She's studying philosophy and ethics, which I found funny and she didn't, and she doesn't eat vegetables, which narrowed the restaurant search in a way I hadn't planned for. She read the framing message and replied with a question I hadn't asked: whether, if dinner went well, it could be the time after. Not this one. The next one. She'd already decided to say yes; she just wanted a dinner between the decision and the doing. I said of course. It's the most sensible answer I've had, and I'd have offered it myself if she hadn't got there first.

Mizuki: slowly

Twenty-one, a French major from Saitama, an idol fan, allergic to alcohol – she says so twice in a profile that runs to two hundred words and four kinds of sparkle emoji. She was apologizing for possibly being late an hour prior to the meeting and then showed up exactly on time. She was similar to Saori and Maru - long straight black hair, a long floral print dress, quiet and confident. A month on the app and already sixty messages a month coming in and four reports on her file, which is a lot of men and a lot of friction for thirty-three days.

Her coffee was the best I'd had in a long time - she was warm, friendly, asked lots of questions and put a hand on my arm on the way to the station. A few days later, she left the App. The LINE conversation has remained warm and friendly.

Her reply to the framing message was one word, more or less: ゆっくり. Slowly. Then a sticker. Then the dinner confirmation, unchanged. It wasn't a no, and it wasn't a yes. It was a woman telling me the pace, which is fair, and I'll take the dinner at the pace she's set and watch how she is in the room. The four reports are a tell, or they're four men who didn't like being told slowly. Dinner will say which.

K: nothing

Nineteen, six weeks on the app, a bright, ordinary profile – baking, travel, easy to talk to – and a thread that had been fine. We had a lovely coffee - ironically, K was also almost a carbon copy of Mizuki, Saori and Maru: slim and petite with long straight black hair, conservatively dressed in a navy top with a gray knee-length denim skirt. Coffee was lovely - warm, friendly and lots of questions. Afterwards, we arranged for dinner. I booked a restaurant, sent the confirmation, and a couple of days later sent the framing message.

She read all three. She's read everything since. She hasn't replied to any of it.

I know what this is because I've written about it before: silence on the one message while answering nothing else is a no delivered the way people on LINE deliver them. What's different is that I could watch it happen in real time – the read receipts arriving, the reply never coming – and could see exactly which message did it. The confirmation didn't. The framing did. She'd been happy with dinner. She wasn't happy with the sentence after it, and she wasn't going to say so, and she wasn't going to pretend otherwise either. Her slot on the 11th went to someone else.

What the four of them told me

Saori said yes and moved it forward on her terms. Maru said yes and moved it back one on her terms. Mizuki said yes but slowly. K said nothing. Four answers to the same sentence, and every one of them was true, and I learned more from one message than from the previous month of threads.

The framing message isn't a line. It's not a technique. It's a door I open a few days early so that anyone who doesn't want to walk through it can leave by the one they came in through, without a scene. Most walk through. Some ask if they can come back tomorrow. And one in four, apparently, looks at the door, reads it twice, and goes quiet – which is not rudeness, or not only. It's the app's way of saying no, and we don't take it personally, because the alternative was K sitting through a dinner she didn't want, and me not knowing why.