Should I Say Something

Absolutely! If you don't, you could be responsible for her death.

I new a woman who was in a similar situation, and warned this woman who was set to marry a very abusive man. I told her in great detail the things he had done. She replied that he had never been abusive and this man had treated her like a queen.

I lost contact with both these people, they did get married. About 5 years later I ran into the woman in a Vancouver. We talked a bit, and I asked if she was visiting Vancouver. She said no, she lived there now. She told me she was forced to leave this abusive man. Soon after they were married, his behaviour changed from Prince Charming, to the cruel and evil person I had told her about. She admitted I was totally correct, and realized he would probably never change. She was armed with the knowledge this abuser had done this before, and she needed to leave, and she did. She thanked me for giving her the common knowledge of that area.

If you fail to warn someone that a man (or woman) is dangerous, violent and even crazy, I truly believe you will in part be held responsible for what goes on, esp abuse, mental sexual, financial or physical.

As for God changing the abuser into a more gentle, kind person, he certainly could. Unfortunately, these people are not Christians, and have no motivate to obey God and become a good husband/wife. Abusers are sociopaths and psychopaths. They have zero empathy, they are extremely controlling, and do not care more for their spouses than themselves and their evil motivations. Never tell anyone to stay with an abuser.

I remember arguing with a long time Christian woman about that. She believed the woman should go back to her abuser and show him the light of Christ. People who can hurt and damage other people without remorse will never be suddenly changed because the spouse returned to be a doormat. They are blind, and cannot see the love of God in their spouse. No woman (or man) should ever have to live in an abusive marriage. In Canada, it is against the law to abuse your spouse. These people can and will go to jail for the crime of assault and battery at the very least! They are criminals. Would you let a criminal continue to batter their spouses/girlfriends? I hope a warning is the least anyone would do.

telling them they are wrong, when they are not!

In which post does he not accuse?

Then in which post does he accuse any person?

In his very first post ~ post # 10. Insinuating that my friend is committing adultery and fornication is the same as accusing him of doing so. The list goes on from there, but you already know that.

Is your friend going to be committing adultery and fornication?
Since he is One Flesh with another woman, this would seem to be true.

There you go accusing people in like manner as your graceless protégé. I’m not surprised.

What is the accusation? Repeating back to you what the Bible says about acts of man is not an accusation. You explained the situation, he has been One with another woman. What is there to miss about that?

Don’t try to back out of it. You’re assuming, thus insinuating, thus accusing these two people of adulterous fornication when you have absolutely no proof or reason to do so. As previously stated to your graceless protégé, your idle words will be held against you.

I know a guy who is not well liked but I treat him well and he considers me a friend. He beat his wife to the point that she left him and now he is dating a girl he knew from high school some twenty years ago. Do I warn her of his abuse, yes or no?

You should rebuke him sharply, disfellowship him until he repents and yes warn her.
They may hate you for it but you.