I've butted in before personally...but I am more likely to call 911 if the threat isn't immediate (rather than jump in). I had a neighbor once who was abusive to his girlfriend, and after I said something once he broke 2 windows on my car.....that ended my desire to personally confront unless I must.

When it comes to kids....I will sometimes say something like, "I know you must've had a long day....and you're at your wits end....but do you really need to..."? Sometimes it works. Most of the people I've seen aren't bad parents, they're just tired. <sigh>

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Life is too short not to love and be loved....preferably multiple times in one night.

I think men talk to women so they can sleep with them and women sleep with men so they can talk to them. ~ Jay McInerney