In the DVD extras for Deathly Hallows Part 2, Daniel Radcliffe interviews J.K. Rowling. That alone would be a pretty great bonus, but J.K. goes for so much more. In the interview she says that about halfway through the series she was in a bad place emotionally and was thisclose to killing to off Ron Weasley.
"I think in my absolute heart of heart of hearts, although I did seriously consider killing Ron, I wouldn't have done it."
She says her original plan was to always never kill off the three main characters but also said she did not plan on ever killing off any of the people she ultimately did kill off so who knows if she would have actually killed off Ron. It would have made for an interesting dynamic later on. Would Harry and Hermoine have ended up together? Who would have saved Harry from the frozen pond? I think J.K. went after the Weasley family so frequently because there were so many of them.
She said she was going to kill Ron just so people would not have him anymore and that she was going to do it out of spite. It does sound like she was in a really bad place when she was writing at that time. I wonder what was going on in her life.