My sim is always happy, even with no moodlets or lots of bad ones. It resets to the proper level when I restart the file. Now, I had a similar problem a long time ago where sleeping in a particular bed caused the sims to be permanently unhappy, so I'm thinking this might have something to do with the "Well-rested" moodlet again. Now, I can try resetting the game folder when I have time to see if that fixes it, but besides that, is there known fix for this? The permanently unhappy bug had a mod made for it that fixed it, and I thought there might be something similar for this.