"At the beginning and end of each performance, Hermes starts and then restarts the story. Orpheus, determined to
win back Eurydice, appeals to Hades by singing the story of Hades’s love for Persephone. Orpheus’s persuasive retelling is echoed by the looping narrative structure of the musical, which opens with the coming of spring, marked by Persephone’s leaving by train to return to the world above."
I find this description of the loop very intriguing. The play itself is a loop of Orpheus and Eurydice's story, but their story is just a parallel of Hades and Persephone's story. It may be about these characters specifically, but it is also just the story of love and tragedy, doomed to repeat for as long as humans love.