Ab minor!
Hi. I think this makes a terrific little prelude. It's simple, sweet, and sad. The harmonies remind me of parts in the opera "Dido & Aeneas"; specifically, "Dido's Lament", which is near the very end.
I'm giving it an imperfect 8/10 because the ending didn't do much for me. Somehow it seemed that the moving 8th notes had already been over with and the piece was drawing to a close, and at that moment you chose to play them again and I thought by then I'd had enough of that motif. Maybe I could be convinced differently after hearing the whole piece, so... happy writing!