May be even a sympton of Borderline personality disorder? I'm most likely wrong though.
But us INFPs feel like there is always something better out there waiting for us..and we long to go out and look for it. Maybe that's the case with your friend? Maybe she is just on an adventure to find her bliss.
Is it that by its indefiniteness it shadows forth the heartless voids and immensities of the universe, and thus stabs us from behind with the thought of annihilation, when beholding the white depths of the milky way?