One of the many reasons why the first half of the Deathly Hallows blew every other HP movie out of the water so badly as to make you wonder whether the same people had made it, was its great take on Harry and Hermione's friendship - but in the book like in the movie, while the friendship makes sense, it's also clear that it's platonic.

Ron and Hermione works on some levels, but as to whether it works in the long run - well, as Larry mentions, that really depends on how they'd evolve in young adulthood and beyond, wouldn't it? If, like most characters in the series, they don't seem to evolve much anymore after leaving Hogwarts, in any way, then sure, why not. At the time of book seven, which ultimately is the only thing we can really discuss, I think it makes more sense than Harry with Hermione. Of course, Hermione with some random other guy whose interests align more with hers could also have made sense, perhaps more. But Harry is hardly that guy, either.

I did like Harry and Ginny, it had that inevitability issue hanging over it admittedly, but Rowling's attempts to give Ginny her own personality from book five onwards while Harry was elsewhere with his thoughts romantically, worked out quite well I thought. Of course if you compare to YA books where the romance and the character development is the focus (like, say, the genius of Aidan Chambers), Rowling's romances all feel a little flat, but considering how they have to fit into the epic story, I'd say she does a commendable job of it on the whole. In the end perhaps it's a little Eddings-esque with the way the protagonists neatly pair up with each other, but at least you've got things along the way like Hermione's relationship with Krum to shake those clichés up a little.