http://www.hypable.com/2014/02/01/jk-rowling-ron-hermione-relationship-regret-interview/ “I wrote the Hermione/Ron relationship as a form of wish fulfillment,” she says. “That’s how it was conceived, really. For reasons that have very little to do with literature and far more to do with me clinging to the plot as I first imagined it, Hermione ended up with Ron.”
Have you seen this? I think it's interesting that she said that she was clinging to the plot as she first imagined it. That explains a lot about the epilogue!