This is usually pretty easy to fix.
1) If they're trying to kill YOU it likely has more to do with how much they hate you rather than their moral. Check out "most hated person" and see how they feel about you. If this is the reason, try giving those who hate you a love potion, or dance for them, or have them follow you around. That should change the tide (love potion is the quickest).
2) If they're going at each other, just pull them apart and stick them outside of each other's territory.
I've only ever had this happen twice. The game typically warns you before it gets ugly.
The first time it happened, I ignored the warning and one of my friendlies tried to kill another one (unrequited love) and got her ass handed to her which I thought was funny. I grabbed the attacker and tossed her in a different camp. Problem solved.
The second time, I heeded the warning and immediately moved the unhappy female to a different area. Problem solved.
To avoid this even happening, check your NPCs' personality traits. The trick to it is to avoid putting together personalities that either hate or love each other. Both can lead to issues. Neutrality is the best course of action.
Also disable "Allow sex" and "Allow love". This will cut down on a lot of the bullshit.
