I shake my head. I mean, I love that book, too. But not now. Not at five. And yet I can’t help hoping that Christian plans to read Marlon the whole chapter. Because his phone just beeped importantly.

A new message!

But it is only his friend – our friend, Spike – confirming tomorrow’s appointment at the gym.

And then I remember Instagram. My husband bloody loves Instagram.

And as I am scrolling through Instagram I feel the first sharp stab of guilt. Because, you see, unlike some people I could mention, my husband’s life is good.

Christian’s timeline abounds with all of his favourite things – physical fitness and electric guitars and images of amusing animals being unselfconsciously adorable. This is what my husband has lurking in the secret corners of his phone.

A skateboarding French Bulldog. And vintage Fender Telecasters. His personal posts are full of family, full of us. Christian, Marlon and me and not forgetting Buddy, our yellow Lab. I am shopping for pain but the shelves, I see now, are all empty. Christian’s phone comes with a delete button, of course. Any keeper of secrets with any kind of experience knows that you do not leave anything on your phone that you would not want written in letters of fire.

And you can always have a second, secret phone.

That’s what I did.

But in my heart, I know that my husband has not been compulsively pressing his delete button or conducting his extracurricular activities on a second phone. Because some people have nothing to hide.

Some people are simply – that word again, because there is no other word – good.

Look how casually Christian leaves his phone lying around for his wife to secretly plunder. In my experience, the truly innocent, the good souls with nothing to hide, are never suspicious because they live with the delusion that the rest of the world is as honourable as them. It is only the guilty who are tormented by suspicion. It is only the guilty who ever go shopping for pain.

I hear Marlon yawn and stretch and protest that – honestly, Daddy – he is not even remotely sleepy. And then much scuffling as the dozing dog is lifted from the bed.

‘Just rest your eyes,’ Christian says, his smile in his voice.

In our family we are always telling each other to, ‘Just rest your eyes.’ Just resting your eyes means there is no pressure to sleep. And without the pressure to sleep, you inevitably sleep. It works for us.

I hear Christian kiss Marlon on the top of his blond mop and I take one last look at our happy faces on his phone, his loving witness of us.

This is his world, I think, a sob of real grief buried deep in my heart.

Me and Marlon and Buddy. This is Christian’s life.

Which makes him sound much duller than he is.

Christian may be a stay-at-home-dad but he is still a major dude. He is tall, lean, muscular, a natural athlete who hones his genetic blessings in the gym three times a week under the watchful eye of friend Spike. In those long hours when I am slumped in my office chair, over-caffeined and carbed-out and work-stressed, Christian is clocking up the high-intensity cardio.