I don't entirely agree. I think that we often assume the police have responsibilities that they not only don't have, but don't have the resources to manage. I see both sides here. The police are not really there to prevent crime or to offer protection services. There is much that could be improved about how they do what is their job - to solve crime and prepare evidence of crime - and some of that lies at their own door, some at the door of government and resources.
I would suggest that, in addition to more support for DV organisations, there is a need perhaps for a service that is there to protect those who need it. Not the police and not social workers - they have their own roles to play. It may still not be perfect, but if you take somebody to court because they owe you money, we have bailiff systems to enforce court orders etc to help you get your money back. Surely people are more important than money? Why not have a "protection service"? It might be a stand alone service, or a specific and seperate section of the police force. But a service whose design is to protect those who need protecting - not a "thin blue line" of officers who are stretched across far too many issues.
That said, even then many vulnerable people will return to, or get in contact with, their partners, for all sorts of reasons, but often simply because they want to believe them, and to believe in them. I recall supporting a young woman a long time ago whose family arranged a forced marriage because she was in a relationship with someone they disapproved of. Over an 18 month period, which included her being drugged and an attempt to take her out of the country in that state, and being locked in an attic room as a prisoner, she went back to her family three times before finally getting it. She had a great deal of support and had refuge places - but she still wanted to believe that her family would not do this to her despite all the eveidence to the contrary. In the end, most people strive to find the good in those they care for, even if it isn't there.