I went back to my room and spent all night contemplating whether it was possible in life not to be constantly let down. If it could ever be worth pinning your happiness to another person, when all other people ever seemed to do was disappear.

I became convinced that I was being watched.Because self was still leaking everywhere, a part of me began to think it was Mizuko rather than a stranger. I hoped that there might still be a reunion. I hoped it in the shy, sly way hope comes out of the jar, the mistranslated box, last—after everything and everyone else has escaped.

It never ceased to amaze me how she just had the facts always, in her head. It occured to me that if, or when, she died, a whole load of facts, a body of knowledge, might disappear without a trace.

Or maybe it was already too late; you only get one first love. She was mine, but I had not been hers. She was only going to look for some echo of it, and if I had made the right noises, that echo might have been me for a while.

That night I dreamt about the roses laid at the wrong feet—the feet of the nurse. Each bit of the dream was like a hyperlink. I pressed on one, wanting answers, and it took me to another. I could never get to the meaning at the bottom of any of the bits. When I reached for the petals of the roses, I was touching a metal seatbelt buckle in a coach, driving by night through a remote place, with a band of mist running parallel to the glass I leant against.

The sharp, superficial pain at being spoken to unkindly had obscured the deeper pain, which had not yet turned into something hard and heavy.

The whole time I hadn't slept with anyone at university had made it harder and harder to finally do it. Like spending too long on a very high diving board, until finally you have to exit ignominiously, the same way you climbed up.

Have you ever tried to organise a threesome in real life?'I shook my head. I'd only encountered them in porn, but it seemed to happen without much admin, the same way all porn skipped out the granular details of sex, like condoms and kissing, that were supposed to happen in real life.

She was convinced a word existed, a noun, that meant the loss of feelings for someone who was formerly loved—a word for the act of falling out of love. I said I couldn't think of it. It wasn't in the dictionary either, not the one she wanted.

Mizuko loved reading the dictionary. She liked it when there were multiple meanings for words and when opposite meanings could be contained.

Waking in the morning, I had to remember grief all over again. It was sunny, a white winter sun, and that made me sad.

From watching Silvia, I'd learned that one of the worst things about being ill is that most people find your suffering opaque. With this sadness it was different. I felt that I needed to nurture and protect it from people's understanding. I wanted Susy's sympathy because I wanted comfort and to feel less alone, and yet I also didn't want it—I didn't want my personal grief to be part of something universal right then.

A neon-pink 3 flickered and instantly disappeared again into the dark. The sight of it on my own device now made me sick. I held my finger down on the menu screen; each little app logo began to vibrate. I deleted the 3. I contemplated deleting everything. Cleaning it all away. The idea had a charm, a self-cancellation, many little suicides, a way to dispatch myself without actually going anywhere.

Though I did not know her exact address, that she appeared to live almost within breathing distance of Robin, and that I lived with him, and that her pictures showed that she was now dating the mysterious Rupert Hunter, our despotic mothers, our absent fathers, the borders we had both crossed, all our many parallels and connections at every point, could not be chance. I saw it as evidence of the hidden connections between things, an all-powerful algorithm that sifted through chaos, singling out soulmates.

I hope when this is done I'll be able to get back into my happy gardening vibe that was so healthy for me. I want to go back to my routine and my morning ritual with the compost, but it will probably be that my life will split in two. New Leaf Gardening in Wood Green will be happening in parallel to a fantasy that runs along the bottom of that screen like a ticker. Alice will be fine. Rabbit will stay up tonight, and every night. Resending and resending, reopening the page to see if she has responded, if anyone has. The spinning wheel will make my eyes hurt and everything else will go dark.

Well, then, what's the plan now? You can't stay here forever.'My plan was indeed to stay there forever.

My ability to make up lies on the spot chills me as much as it saves me.

There was never one truth. Even the Higgs could still be used to prove opposing theories, its mass falling between them on a chart. Besides, I told myself, my breathing heavy, eyes widening until they bulged, I was post-truth.

Have you ever truly, keenly felt like you don't know who you are? Do you ever do something and think, Who is at the controls? Like some mad pilot has locked you out of the cockpit? I definitely do. I feel a kind of vertigo that makes me shake afterwards. I guess we all feel it when making a difficult-seeming choice, and sometimes you seriously don't know what you want because you don't know who you're supposed to be, or who you want to be. Physics, my first and second families, my philosophy degree, had all failed to help me answer that question. The former has led me to wonder whether I am one of an infinite number of Alices in multiple universes. A quantum fuck-up, which is someone who fucks up in every one of those universes but in different ways.

I saw her note the way I hovered over the various ethnicities on the form. First the 'white' box, then to the airspace over the 'black' box, a kind of momentary hesitation, a protest of stillness, a staring into the abyss of everything I did not know about myself. She, like me, was made of halves.

I felt the nauseous shiver in my stomach—everything from rage to empathy to morning sickness—that I had grown used to and now thought of as being love.

The messages must be stuck somewhere in the tube of light underneath the ocean that connects London and New York.

At first, sending the confession by real mail had felt like a genius device. I would not have to sit by my phone and watch for the signs that indicated it had been sent and seen. Slim but solid paper would, I hoped, convey me better. Now I had to consider the very real frailties of the system. Ludicrous, in fact, to entrust something of such magnitude to a mailman. A perfect stranger. I looked up stories of nefarious New York mailmen. There was one who has willfully upturned the lives of ordinary people like myself by hoarding 40,000 pieces of undelivered mail. The city was crawling with thieves and malcontents.

Email is the scourge of our age,' said Silvia. 'Email and cancer.

Maybe, as Mizuko said, we won't even really die, just carry on in the feedback loop we are stuck in. Instead of connecting with new things, widening our worlds, algorithms have shrunk it to a narrow chamber with mirrored walls.

I found it hard to write the bits where the things that were at first surprising or even shocking became normal incrementally until I couldn't see that they were anything but normal, because everything else had shifted just one centimetre here and one centimetre there, moving at the speed fingernails grow, until finally everything just clicked into exactly the wrong place.

She told me it was unlucky to share a reading with others, but the main point, the one I don't mind mentioning because it seems relevant to the story, is that she said I had a kind of evil spirit following me. 'Obviously,' she added, 'that sucks. But if we get you some amber—

I was on the sidewalk, buffering, wondering if it was okay to follow people in real life.

No order, no pattern, just chaos. Lots of little universes separated by invisible screens . . .

I couldn't decide what kind of person she was, whether she was one of those insects that look exactly like wasps but aren't . . . I just wanted to know if she would sting.

In the last week I felt her withdrawing. What was once everywhere, an ocean I imagined myself to be drowning in, was now barely deep enough to bathe in. I saw her warmth draining away and I couldn't stop it.

I saw a doctor. I went in case there were any remnants of the summer inside me—sticky, slender fish bones that needed to be scraped into the bin. He was dismissive of my concerns and said my body would have let me know by now. Did I have what was known as female intuition? I said I'd had my feminine intuition somewhat scrambled in the past.

I began to cry but maintained my shouting through it, like a wind through sheets of rain.

For a while this seemed to do the trick, and I felt that whatever contamination I had helped to spread, the boundaries I had helped to break, sprinkling flakes of myself all over the surface of New York like so much fish food, had been forgiven.

Was this what the city would look like when knowledge was no longer enough? When the desire to turn inward, surrendering entirely to one's own private world of nonresistance, overwhelmed, like creeping ivy, our desire to know worlds beyond it?

Man with goatee. Man who looked like a Beatle. All the Beatles at once. Woman wearing newspaper hat. I'd grown used to how weird New Yorkers were, and I could fit them into types.

The glow of the steetlamps sat heavy and thick above me. As I walked aimlessly, in the direction of downtown, I returned to my theories. That Mizuko and I shared the pictorial equivalent of DNA. That a sympathetic magic existed between us, no matter how far apart we were pulled. That we defied physical laws of time and space, waves, gravity, the rules laid down by physicists which governed our physical universe (earthquakes, tsunamis) and physical bodies. And yet somehow our connection had led to the opposite of intimacy. My search had led to its opposite. I had never felt so isolated and disconnected, even from myself.

She was limp and pathetic and woozy and I loved her, I realised, even more because I knew how completely it was doomed.

We had, I felt, bared small pieces of our symmetrical souls to each other, fast, as if playing one of those breathless card games, and I had pretended to be as moved as I had been the first time I uncovered it all myself, back in East Hampton.

Yeah!' I said again, widening my eyes and nodding slowly but emphatically to show that she had seen into my own symmetrical soul.

To me, it was clear proof of the existence of supersymmetry, the idea that every particle has a partner. She was mine.

Suddenly I had to laugh. It was like realising you definitely need to projectile vomit when you thought you had it under control in some imprisoning form of public space.

It's hard to explain how an infatuation actually starts. It's a state so all-encompassing that it's almost impossible to remember how it felt to live inside your own head before it began. Everything that precedes it becomes a pathway that was always leading there. Time before is valuable only as a resource with which to create a persona, to bind the object of the infatuation closer. I had given my (partially fabricated) past life to Mizuko to make a story that in the end never got told. Or not by her. It is also hard to explain the intensity of the infatuation itself. There is rarely an explanation that seems reasonable to anyone but you. Unless you're part of a cult or viral phenomenon, so that when you weep outside the object of your infatuation's hotel room, you do so in the company of millions.