‘What is it?’

‘Just present for my mother.’ She waved a hand. ‘But Leonard thinks I spend too much on my family so I don’t want him to know everything that I send.’

I humped it down to the FedEx office at West 57th Street and waited in line. When I filled out the form with the assistant, he asked: ‘What are the contents? For Customs purposes?’ and I realized I didn’t know. I texted Agnes and she responded swiftly: Just say is gifts for family.

‘But what kind of gifts, ma’am?’ said the man, wearily.

I texted again. There was an audible sigh from someone in the queue behind me.

Tchotchkes.

I stared at the message. Then I held out my phone. ‘Sorry. I can’t pronounce that.’

He peered at it. ‘Yeah, lady. That’s not really helping me.’

I texted Agnes.

Tell him mind his own business! What business of him what I want to send my mother!

I shoved my phone into my pocket. ‘She says it’s cosmetics, a jumper and a couple of DVDs.’

‘Value?’

‘A hundred and eighty-five dollars and fifty-two cents.’

‘Finally,’ muttered the FedEx employee. And I handed over the money and hoped nobody could see the crossed fingers on my other hand.

On Friday afternoon, when Agnes began her piano lesson, I retreated to my room and called England. As I dialled Sam’s number, I felt the familiar flutter of excitement just at the prospect of hearing his voice. Some days I missed him so much I carried it round like an ache. I sat and waited as it rang.

And a woman answered.

‘Hello?’ she said. She was well-spoken, her voice slightly raspy at the edges, as if she had smoked too many cigarettes.

‘Oh, I’m sorry. I must have dialled the wrong number.’ I briefly pulled the phone from my ear and stared at the screen.

‘Who are you after?’

‘Sam? Sam Fielding?’

‘He’s in the shower. Hold on, I’ll get him.’ Her hand went over the receiver and she yelled his name, her voice briefly muffled. I went very still. There were no young women in Sam’s family. ‘He’s just coming,’ she said, after a moment. ‘Who shall I say is calling?’

‘Louisa.’

‘Oh. Okay.’

Long-distance phone calls make you oddly attuned to slight variations in tone and emphasis and there was something in that ‘Oh’ that made me uneasy. I was about to ask whom I was talking to when Sam picked up.

‘Hey!’

‘Hey!’ It came out strangely broken, as my mouth had dried unexpectedly. and I had to say it twice.

‘What’s up?’

‘Nothing! I mean nothing urgent. I – I just, you know, wanted to hear your voice.’

‘Hold on. I’ll close this door.’ I could picture him in the little railway carriage, pulling the bedroom door to. When he came back on he sounded cheery, quite unlike the last time we had spoken. ‘So what’s going on? Everything okay with you? What’s the time there?’

‘Just after two. Um, who was that?’

‘Oh. That’s Katie.’

‘Katie.’

‘Katie Ingram. My new partner?’

‘Katie! Okay! So … uh … what’s she doing in your house?’

‘Oh, she’s just giving me a lift to Donna’s leaving do. Bike’s gone into the garage. Problem with the exhaust.’

‘She really is looking after you, then!’ I wondered, absently, if he was wearing a towel.

‘Yeah. She only lives down the road so it made sense.’ He said it with the casual neutrality of someone aware he was being listened to by two women.

‘So where are you all off to?’

‘That tapas place in Hackney? The one that used to be a church? I’m not sure we ever went there.’

‘A church! Ha-ha-ha! So you’ll all have to be on your best behaviour!’ I laughed, too loudly.

‘Bunch of paramedics on a night out? I doubt it.’

There was a short silence. I tried to ignore the knot in my stomach. Sam’s voice softened. ‘You sure you’re okay? You sound a little –’

‘I’m fine! Totally! Like I said. I just wanted to hear your voice.’

‘Sweetheart, it’s great to speak to you but I have to go. Katie did me a big favour giving me a lift and we’re late already.’

‘Okay! Well, have a lovely evening! Don’t do anything I wouldn’t!’ I was talking in exclamation marks. ‘And give Donna my best!’

‘Will do. We’ll speak soon.’

‘Love you.’ It sounded more plaintive than I’d intended. ‘Write to me!’

‘Ah, Lou …’ he said.

And then he was gone. And I was left staring at my phone in a too-silent room.

I organized a private view of a new film at a small screening room for the wives of Mr Gopnik’s business associates, and the hors d’oeuvres that would go with it. I disputed a bill for flowers that had not been received and then I ran down to Sephora and picked up two bottles of nail varnish that Agnes had seen in Vogue and wanted to take with her to the country.

And two minutes after my shift finished and the Gopniks departed for their weekend retreat, I said no thank you to Ilaria’s offer of leftover meatballs and ran back to my room.

Reader, I did the stupid thing. I looked her up on Facebook.

It didn’t take more than forty minutes to filter this Katie Ingram from the other hundred or so. Her profile was unlocked, and contained the logo for the NHS. Her job description said: ‘Paramedic: Love My Job!!!’ She had hair that could have been red or strawberry blonde, it was hard to tell from the photographs, and she was possibly in her late twenties, pretty with a snub nose. In the first thirty photographs she had posted she was laughing with friends, frozen in the middle of Good Times. She looked annoyingly good in a bikini (Skiathos 2014!! What a laugh!!!!), she had a small hairy dog, a penchant for vertiginously high heels and a best friend with long dark hair who was fond of kissing her cheek in pictures (I briefly entertained the hope that she was gay but she belonged to a Facebook group called: Hands up if you’re secretly delighted that Brad Pitt is single again!!).

Her ‘relationship status’ was set to single.

I scrolled back through her feed, secretly hating myself for doing so, but unable to stop myself. I scanned her photographs, trying to find one where she looked fat, or sulky, or perhaps the recipient of some terrible scaly skin disease. I clicked and I clicked. And just as I was about to close my laptop I stopped. There it was, posted three weeks previously. Katie Ingram stood on a bright winter’s day, in her dark green uniform, her pack proudly at her feet, outside the ambulance station in east London. This time her arm was around Sam, who stood in his uniform, arms folded, smiling at the camera.

‘Best partner in the WORLD,’ read the caption. ‘Loving my new job!’

Just below it, her dark-haired friend had commented: ‘I wonder why …?!’ and added a winky face.

Here is the thing about jealousy. It’s not a good look. And the rational part of you knows that. You are not the jealous sort! That sort of woman is awful! And it makes no sense! If someone likes you, they will stay with you; if they don’t like you enough to stay with you, they aren’t worth being with anyway. You know that. You are a sensible, mature woman of twenty-eight years. You have read the self-help articles. You have watched Dr Phil.