That's not an easy question. It's very hard for police officers to intervene in domestic violence cases, particularly when the arguments and assaults are about the children.
Police officers' two main missions are to intervene in domestic violence cases and mental health issues. Some officers tell me they take up 80% of their duties. They're the toughest cases because the officers deal with couples who are fighting and, in 90% of those cases, the aggressor is the man.
I consider police officers' work admirable.
What I would tell the officer you're going to meet is that he should ensure his work doesn't undermine his mental health. I'm sure that, by the time he goes home at night, he has spent his entire shift with people who fight each other. Encourage him to seek help should he need it and to focus on good mental health because it isn't easy to resume the same work in the same circumstances every morning.