Few things bring me greater joy than someone taking two weeks to reply to a WhatsApp message. I mean it. This week, my friend and former teacher replied to a message I sent asking after his knee, with a very friendly and funny message. It had taken him a mere 24 days to respond. Glorious.

Not only does that kind of slack immediately take any pressure off me to reply there and then, while trying to simultaneously slice a potato, open a box of magnets for my son, load the washing machine and turn down the radio; but it proves the two of us have enough mutual affection and respect that, at some point, we can just pick up where we left off. Have I replied to him yet? Of course not. I’ve had cables to untangle and rice to boil. But I will.

This kind of rhythm reminds me of conversations I used to have with my cousin; they would sometimes be interrupted by three weeks’ absence (we lived in different cities), but then restart exactly halfway through that abandoned sentence, the moment we met at the front door.

A few years after that same teacher introduced me to the poetry of Philip Larkin, I was given his Letters to Monica. I absolutely love the way the shiny-headed misanthropist opens his letters to her – never apologising for the slow response or creeping towards guilt. Instead, it’s all “Dear Furry-Face” or “Bun Dear, Wuff!” Even in one of his low moods (and there are plenty) he begins a letter with: “Dearest Ears, Soured by my evening meal, heavy with gas fire fumes, I take up my pen in general despondency.” Dearest Ears! I love it.

A delayed response isn’t a slight against you; it is a licence to take your own time to reply. It is permission to come back only when you want. Which is why, if you are my real friend, you can keep me on “Read”.

• Nell Frizzell is the author of Holding the Baby: Milk, Sweat and Tears from the Frontline of Motherhood