I think this is a nice start, it might take a bit more poking at though to distinguish it more from the source.
I do agree that it could build up into something more for the middle, it feels like it's swelling up so far but doesn't quite make it before tying it all up. At the same time I feel like cautioning against going overboard with what it is built into.
This really reminds me of the ending of the main story, maybe it's the same song I dunno. (The end of the main story seriously made me cry, I'm such a pansy, but it really spoke to me). I hope you keep working on this and get something even more lovely to listen to out of it. (I also hope other people swing by to give it some feedback).