Why do police abuse their wives / girlfriends so often?

Let’s stick with law enforcement, since that’s the topic of the op (and i will stipulate that military personnel are subject to different forces).
IT’S NOT THE JOB! Violent people can be found in all walks of life. If its true (and I don’t know that it is) that law enforcement jobs attract violent people; well, they are violent people before they take the job. By saying that police work is just too hard to turn off at the end of the day, you’re doing a great disservice to the thousands of men and women who are, indeed, able to turn it off.

And, just for the record, I DON’T want these men and women to do violence on my behalf. I want them to do their job. And while that job may include escalated levels of force, from time to time, it does not and should not include violence

mc

Many professions attract people of a certain ‘type’. Actuary, truck driver, lawyer, doctor, librarian, software engineer, chef, rocket scientist, chess player.

Cop.

That does not mean that all people in that profession are of that profession’s type. It means there is a definable, correlatable predominance of that type within the entire population of people in that profession. The characteristics that make someone an excellent chess player are very different from those that make someone an excellent cop.

So while violent people do exist in all walks of life, I suspect the percentage of all cops who are violent is higher than the percentage of all chess players who are violent. I say this not to bash cops, who perform an invaluable service to our society, but as an observation of what skill set is needed for that profession. And physical violence is part of that skill set. And ‘violence’ here is not uncontrolled temper and rage manifesting itself in a violent reaction. Violence is a physical tool to be used in a controlled, calculated manner when the situation calls for it. But we are all human, with the frailties of the human condition including emotions and stress and worry that can affect us on any given day.

I’d rather be standing next to a chess player who’s having a bad day than a cop.

except that it’s not

mc

Disagree. Sometimes physical force with the intent to hurt someone is needed by a cop to subdue an unruly or dangerous person intending and trying to cause harm.

You disagree with what? The dictionary definition of violence?!
Not only is violence not a “skill” required for law enforcement, it is BY DEFINITION expressly prohibited from use.

mc

As I said above, sometimes physical force with the intent to hurt someone is needed by a cop to subdue an unruly or dangerous person intending and trying to cause harm. Do you agree with that or no?

I disagree. The intent should not be to cause harm - harm can happen but it should never be the objective. The objective should be a subdued individual, not a bleeding one. If all ways to subdue will cause harm, then harm will happen - but it isn’t the objective.

Okay, yes. The primary objective is to subdue the person. Not to injure.