I think with Cho/Harry, there will be obvious repercussions and she may even end up crying on him again, but romantically, it's over for them.

I dont think Ron knows exactly how he feels, JK said there's something going on between R/Hr, but Ron doesn't quite know it yet. I think Hermione does, but perhaps she's closed about it because she doesn't want to be rejected by someone like Ron who's her friend and who's been there through everything.

Luna liking Ron is definately and has already caused sparks to fly between Herm and Luna and Hermione definately became jealous of the fact that Luna liked Ron in OoP. Overall, Luna is the catalyst that they need to push them together. Luna has helped Hermione realise she's getting jealous over Ron.