1.) Alone on a Friday Night? You do You! by Hexagonal-Bipyramid
Loners can show up on community lots or as a walkby, but less often than Sims without this trait.
2.) Wannabe Moodlets by Hexagonal-Bipyramid
If you play or have played TS3 or TS4, you may be familiar with Moodlets. This mod implements the concept of moodlets in TS2. It’s not as in-depth as the later games since TS2 calculates mood differently than TS3 and this doesn’t completely change the way it works since this is not TS3. So the “moodlets” are about the Sims’ surroundings (according to their traits) and the traits themselves. They are invisible, but you can see the change in the Sim’s mood bar.
– Loners will have their mood decreased by 10 if there are 3 or more Sims in the same room as them (or somewhat close to them if outside). Ghosts and pets don’t count. If they are alone, their mood increases by 10.
Everything Sims 2 