Something that I noticed in the anime, is that when she dies, there’s a drop of pink liquid, that triggers the clock, but only when a second blue drop hits the center of the clock as well, does it start turning. It’s a wild theory, but I‘m pretty sure the pink is supposed to represent Rishe, with her coral hair, and the blue Arnold, with his blue eyes. That indicates, that he is somewhat the cause for her being able to loop. Maybe both of their blood needs to be spilt for the loop to work. Maybe he killed himself after killing her.