This is a great idea: building a Neville/Luna relationship despite who marries who in the end. I really like Luna, how even though she's older, she still has the same way of viewing the world.
One little typo I noticed:
"it’s supposed to be natural habitat of the Bainodendrons, you know?"
Isn't it "to be 'the' natural habitat" ?
Anyway, great job! I really like the bittersweet ending.
I was really sad that J.K.R. didn't put them together! But you gave us a great glimpse into what that would've been like. And of course, that song is already timeless. It was a good choice to use it :)
That was so sweet! I'm a big fan of this ship too and I really think you did it justice :) I read your other fic Albus Potter and the Midnight Thief, so I thought I'd check out some of your other stuff and this caught my eye. I really felt for Luna at the end and I think you matured Neville well without compromising the Neville of the books - great job!