Hera was one of the Beings who was known to ancient Humanity as one of the Greek gods. When the Beings were no longer worshipped by Humans, they felt a loss of purpose. Hera was among the first to give in to despair, and, as described by Apollo, she "returned to the cosmos on the wings of the wind", spreading her immortal power out to a point of no return. (TOS episode & Star Trek 7 novelization: Who Mourns for Adonais?)