The end of the group, as a whole. It happened suddenly and without warning, for many members, and many heartfelt posts were made thanking everyone for their hard work. Citta held a special place in many peoples' hearts. The new group's creation lessened the blow somewhat.
Inevitably followed when True Companions were separated once the characters return to their own universes. This was invoked in spades in the last days of the group, when characters were aware of the city's and their new lives' ends.
The death of Desmond after sacrificing himself at the end of the Motherlode event.