Does something exist if nobody is aware of it's existence?
Say you were to indulge in extreme-hermitting, hidden away in a tree house in the Amazon rainforest or among towering stacks of scrolls and books in the Vatican vaults perhaps. Lost to the world, you would turn into a social analog of Schrödinger's cat.
Very much aware that you yourself exist of course. To your social past, an uncertainty. But gradually you become less than a ghost for the collective awareness and memory of the universe. Finally you couldn't even be banned from thought anymore, not even if anyone wanted to, because to ignore something you need to know it's there in the first place and that information may have been lost.
If the Newtonian principle of actio = reactio were also true for perceived reality: does that mean that over time you start to slowly stop existing to yourself because you exist to nobody else?