Ideas
Since one of the most recent patches (not sure exactly when it started), my sims have been randomly starting fights with their friends or even sims they just met. The first sim I noticed this with was erratic/genius/perfectionist/self-assured, and now it happened with a sim who is hot-headed/bookworm/music lover/squeamish/self-assured/paranoid. There were no negative sentiments in either case.
I also noticed a married couple from another household, who previously had a good relationship, repeatedly fighting each other. "Fight!" is also coming up as one of the first options in the pie menu for my couple who have max friendship and romance bars, no negative sentiments, wholesome dynamic etc., and it seems to be being selected autonomously. It might be triggered by negative emotions - I think even the Sad emotion causes it to come up.
This started recently within the last 2 patches, it never happened to any of my sims before, even Mean or Hot-headed sims, and they used to need at least 50% of the friendship bar to be red. It's really annoying, since I don't want all my sims to despise each other or get the "first fight" milestone...
I have the exact same problem. never noticed the traits they have but the “fight” interaction comes in first clicking on another friend/ spouse sim and even without me choosing it they fight. thought to override it with mcc mod, turning off auto mean interactions but haven’t tried yet.