I didn't pay attention in Philosphy class, but in thinking back about Sartre, I found a new translation of Being and Nothingness from 2021, the review for which states (I haven't read it, don't intend to) in part: we alone create our values and our existence is characterized by freedom and the inescapability of choice. Far from being an internal, passive container for our thoughts and experiences, human consciousness is constantly projecting itself to the outside world and imbuing it with meaning.

I take this to mean that every (wo)man is an island.