It was news to me that the actor Dakota Johnson was even going out with Coldplay frontman Chris Martin, but it’s already at the nth degree: Johnson was spotted on a coffee run with Apple Martin (his daughter with Gwyneth Paltrow, for the uninitiated). To cope with these new developments, Johnson has apparently enlisted the $400-an-hour help of Alison Task, a “stepmom coach”. Fine, fine, in the Keynesian sense. If one person has a lot of money and another person is willing to charge them a fortune for something, at least it keeps cash circulating. But there are ways to learn this without paying $400 an hour, so long as you accept that the learning is lifelong.

My stepdaughter is 11. I’ve known her since she was eight. Shortly before we all moved in together, I read a brilliant book, Helping Children Cope With Divorce by Edward Teyber, that said it is two years before a child will accept a step-parent’s authority. So I very rigorously didn’t assert any authority for two years, by which time everyone was old enough (my son is the same age, my daughter two years younger) to point out that my authority was like a vuvuzela at a football match, ambiently loud and incredibly inconsequential.

Step-parents have a bad name - and not just in fairytales – as people who are extremely proximal but not necessarily loving. As such, we are rigorously policed. That’s quite hard to take when you know you are loving, but you have to take it, because you’ll make mistakes and you won’t necessarily notice, especially when it comes to favouritism. If you make a judgment call on whose turn something is and your partner’s eyebrow twitches, it means you got it wrong. If you really find it impossible to adjudicate fairly, you’ve got to do French rugby rules (whoever’s fault it was last time, it’s someone else’s this time) or Dictator for a Day (one member of the family gets everything their way all day, in rotation).

The relationship between older children – teens and above – and step-parents without their own children has completely different challenges, which are mainly about the attention of the parent. A lot of step-parents dealing with children who are basically adults often think their offspring should be cockahoop that they have found love. The opposite is true: even adults aren’t adults when their parent finds love.

It is often assumed that, in an ideal world, there wouldn’t be step-parents and step-children; which is funny, because the relationship is actually quite beautiful. You have all that love and protectiveness, without the freight of guilt. A lot of us know this from our relationship with our own step-parent, but we never extrapolate, we just assume we got lucky.