Ideas
PLEASE refer to Bra1nBlast3d 's comment below - the random spontaneous fighting issue is separate from the other issues in this thread and was introduced with the pre-AA patch. It should not be combined in the same bug report here and I really hope it won't get overlooked because of this.
The issue: a lot of my sims are now getting random enemies because they somehow spontaneously start fighting. For example, a brother and sister with 80% friendship and a Close dynamic, no negative sentiments and no Evil or Mean traits, will randomly start fighting each other and as a result go from good friends to despising each other in 2 seconds. "Fight!" also occasionally comes up on the first pie menu, even if they're not in a bad mood. This never used to happen unless the sims already disliked each other. They also get a milestone for fighting, so it can't be erased entirely with cheats. It's really damaging to gameplay to have relationships autonomously ruined just like that.