It looks as if Nigella Lawson is moving out of the house she shared with Charles Saatchi. Twitter is almost entirely supportive of this but I want to sound a note of caution.

On average, women in a violent relationship leave it 7 times before the final break is made. There are many reasons for this including becoming literally destitute; children begging her to return or badly missing their school and friends; social pressure to look after a man with a mental or physical health diagnosis; finding a refuge too difficult to cope with; the seduction and entreaties of the perpetrator; her own feeling of emptiness and misery; threats made against the life of her children.

If Nigella is moving out for good, then good for her. Bear in mind that she has the personal resources of financial stability, a powerful family and a sympathetic media to make that move less gruesome. And if she moves back in with Saatchi then that’s fine too. We expect women to be ‘brave’ and ‘strong’ and ‘proactive’, to end a relationship within a moment of the first slap but it’s so much more complex than that. The slap is often the first physical expression of violence. Months, even years, of financial and psychological violence can lead up to it. I’ve lost count of the women who’ve said, ‘I wish he would hit me then there’d be proof he was violent.’

Part of the isolation that women who experience domestic violence are subject to is when their friends and family get frustrated with them for staying with the person who hurts them. There’s no doubt that it’s exasperating and exhausting when a woman chooses to remain in a situation that is so clearly brutal but giving her ultimatums – “If you stay with him I can’t be your friend any more,” – is a reflection of the abuse she’s been subjected to – “If you go out with your friends I’ll punish you.”

Women leave when it’s safe to leave and when they’re ready to leave. Not when someone else wants them to leave. That’s the point: They’re ready to think for themselves again rather than just do what someone else wants them to.

The pictures of Nigella Lawson crying as her husband held her by the throat, twice with one hand and twice with both hands, have gone around the world. Because both of them are public figures domestic violence is at last near the top of the news agenda, even if it’s tilting more towards Celebrity ‘News’ rather than Criminal News.

The lunchtime BBC report seemed to play the incident down. Saatchi says that they were having a ‘playful tiff’, that Nigella wasn’t crying because she was physically hurt but because she hates arguments. The news reported that she went home with Saatchi, and a witness – one of many who did nothing and said nothing at the time – said “She had a real look of fear on her face. And yet she kissed him.”

This is intimate partner violence, also known as domestic violence. ‘Domestic Violence’ is the term used by most people who work in the field but we’re aware that the term ‘domestic’ can be problematic. It implies something to do with houses and housewives and private life that is no one else’s business, as we can see demonstrated when a man starts choking a woman in public and no one does a thing about it.

Imagine what would happen if a stranger walked up to Nigella Lawson and put his hands around her throat. All hell would break loose. The police would be called. Members of the public would leap to restrain him. Nigella would be taken to a safe place and comforted. But because a husband does the same to his wife it’s a private matter. Strange. And entirely illustrative of the problem.

So why would Nigella meekly kiss this man then get into a cab and go home with him?

All the research shows that when a woman who is in an established abusive relationship tries to leave the violence increases. Her abuser is outraged that she has the temerity to want to make a decision about her life. He threatens her with loosing the children and her home, threats that are very real – in most cases it is the abused women who has to leave her home rather than the abuser who is made to leave. If she leaves she will have to loose everything and begin again. She needs to disappear because abusers hunt people down ruthlessly. They do not stop.

She is put under greater surveillance; her mobile will be taken away or he will make a point of reading texts sent to her and monitoring who she’s calling. Her emails and internet use are monitored. He tells her friends that she’s going through a funny phase, going a bit strange, that he’s having quite a hard time caring for her but it’s ok, he doesn’t need any help because he loves her so.

Every 6 weeks or so the news will report a man killing his partner and often his children and usually himself. Sometimes he’ll kill the children and himself because to have your children murdered is the ultimate, never ending, perfect abuse. The neighbours will all be very shocked and say things like, “He was such a good father! They all looked so happy together, a normal happy family!” This is family annihilation, a phenomenon that seems to either be increasing or being better recognised, and it most often occurs when an abused woman tries to leave. And this is a really good reason why lots of abused women do not leave. Because they know that their lives and the lives of their children are at serious and genuine risk.

Because Nigella Lawson is a public person it’s unlikely that Saatchi will attempt any of this, it will be too easily exposed. I know nothing at all about the private life of Nigella Lawson and Charles Saatchi but I might ask a few questions of a couple in a similar situation:

Why wouldn’t she immediately pull away in shock and horror?

Why wouldn’t she stand up and leave?

Why didn’t she call for help? Or contact the police?

But the real questions, the most important questions I’d ask are not about why a person being choked does anything. It’s really not about her – she’s being choked, her options are somewhat limited. The questions I’d ask are about the person doing the choking:

Why does a man think it’s reasonable to choke his wife, in public, four times?

And if he does this in public, what goes on in private?