I suppose there are two possible explanations for cops having such higher rates of violence against their partners, relative to the general population.
First, it could be that people with a tendency to violent and abusive behavior disproportionately gravitate towards law enforcement work, because of something specific to their personality types.
Secondly, it could be that the conditions of the job put cops on a violent hair-trigger, which they can’t easily turn off after going home.
But either way, the results are the same, and the results are the problem. Something has to be done, beginning with figuring out ways to break down the bullshit blue brotherhood (and it is mostly, still, a “brotherhood”) that protects abusive officers, whether their abusiveness transpires at home or on the job and in the streets.