Recently I read of a work by Alvin Lucier, 'I Am Sitting in a Room' (1969), that created a bell-like effect on a vocal recording by recording the piece being replayed in the room where it was recorded. I've tried to do something like that here using a modeled studio, as well as some crazy reverb. It didn't really work but neither did the idea I tried earlier in the day, so this is what I've got.
I like the sense that the drifting apart is heard in the increasing reverb, with its implied emptiness.