These murders are extremely predictable, actually.
It's nothing to do with friends and family being uncaring and everything to do with our culture which blames victims and validates unhealthy relationships as being normal, even presenting some aspects as a good thing e.g. jealousy.
Domestic violence organisations and experts can tell you that there are clear signs that relationship violence is escalating. Perfectly nice men don't just suddenly turn violent - there will have been signs in this relationship, you sometimes see these referred to as "red flags". Possibly, the abusive behaviours present in the relationship led to the break up. We know for a fact that women in abusive relationships are most at risk when the relationship ends. Currently, many domestic violence shelters and support services have lost funding due to cuts.
One of the reports has an ex-neighbour of the man saying that, actually, he was a man who was prone to aggression towards neighbours and anyone who displeased him. This is another sign that we know - unfortunately in his case these incidents were unreported.
If you can stomach it, Women's Aid have a report called "Nineteen child homicides". This details incidents where children are killed by their father after divorce/separation where domestic violence was present in the parents' relationship. It is not exactly the same scenario, but it is close. We have information. Nobody is acting on it. Why? There are only two logical conclusions, each horrifying. The first is that nobody cares. Or the only people who care are powerless to effect change. The other conclusion is that there are just too many men who fit the profile, so that it would be a logistical nightmare, not to mention a threat to civil liberty, to keep tabs on them all.
I think attitudes need to change first so that the smaller incidents are more likely to be joined up. Things are changing - but as 99% of the reports of this and other similar incidents show, we have a long way to go.