The fear that your deepest connections with people are ultimately prettyshallow - that although you consider them close, you refuse to let them see the “real” you. Due to fear of losing them after you expressing your fears, hopes, or love to them.
Fear of nothingness (comes from the combination of the Latin word nihil which means nothing, none, and the suffix -phobia)
Voyager's morale officer and chef Neelix suffers from nihilophobia, having panic attacks while the ship was traversing a dark expanse of space known as the Void.