i cant say i have ever noticed anything between balthier and ashe at all . I think that is just reading into something which isnt there.However i thought it was fairly obvious that "something" was between fran and balthier even if it was only that they cared for each other a great deal.
And i dont think ashe and vaan had anything for each other except some kind of sympathy about losing loved ones ( ie rasler and reks)
Thats how i see it anyway.