We don't need to argue about this; if you change society's perception of abuse, women will naturally see it as less acceptable, feel more able to leave, lean more towards avoiding men who show red flags or danger signs. It seems as though it is most urgent to start here, but that's backwards - by the time the woman is in the relationship it's pretty much too late, when you look at the bigger picture (of course it's never ever too late for an individual to change their own life by getting away from toxic people and absolutely it's valuable and crucial for individuals to do this).
How do you think that abusers get the way that they are? I'm sure some of them are straight up psychopaths but for a great, great number they are repeating patterns and lessons they learned about relationships in their own childhood. Attitudes of entitlement, of sexism, the premise that violence is masculine and inevitable. Some of that is cultural.
It would be nice to pretend that abusers, rapists and psychopaths fit into a nice neat little box and that they are anomalies, outliers, that we can avoid them and be okay. But I think that taking this mindset is sticking your head in the sand - the numbers are too great. Women can't avoid all men who act in these ways because - I don't know the numbers, but I reckon it's easily over half of all men. Astounding numbers. And yes, of course not all men. We don't need to hide away from or vilify all men.
When you advocate that individuals should act, that we should teach women to see the signs, you are treating the symptom. Attack the cause and the symptoms will shrink too, just more slowly. Yes more women and children will suffer in the short term, but by focusing on society as a whole, fewer women and children suffer in the long term.
Nobody deserves for their children to die. It is awful, the worst thing imaginable. She could make the worst mistake in the world - clearly, she did. She still did not deserve the outcome.