I don't think it would have worked out personally-dating someone at school is hard (especially in hogwarts)-although i love romione and hermione going with someone else was sad i think it was good for them both to get over other people and move on! They'd have to go through all the other rows they go through during the rest of the book and the next so-i think they'd have fallen apart!
Hermione would have gone with Ron but Ron clearly wasn't ready for it because he went out with Lavender!
I don't think the relationship would have failed I just think it would have just happen sooner then it did which IMO was well over due you could tell through the movies that the love between them had become really strong through every movie as the saying goes "its better late then never" =)
