Ideas
I came back to a household I hadn't played in a while and immediately my couple who are engaged and who I left happy are unsatisfied in their relationship. Then they autonomously started a fight during a happy conversation. I built their relationship back up from a full red friendship bar and it happened a second time and ruined their relationship again.
This is happening in my save as well. It's a long-legacy (2+ years old) save and does make for some great story telling, but it's upsetting to see my patriarch get in a fight with his long time best friend, now spouse, out of no where and their entire relationship blow up because of it.
Playing on PC in Oasis Springs without Eco Lifestyle (so no active NAPs).
Three separate fights broke out between different members of my household and their long-time friends.