Not sure if mods are in play here at all, but with NRaas Tagger I can watch over what inactive sims are doing and where they are going. Very often I see sims who have visited any kind of rabbithole lot to engage in activities together, so that can be eating, seeing a movie, the big game, a planetarium show, etc. do leave the rabbithole independently of each other as they may have entered at different times and there could be significant traffic around the entrances/exits. Quite often they will leave from different exits, if there are more than one, and will find other things to do while the ones they were with are still inside even if this is meant to be a formal group-up or date. I see it as part of the game to keep track of them, somehow, and engage them in some activities if the active ones leave first (if possible) so that the group, formal or informal, can stay together when all are finished up inside.