In the end, Harry had snapped and said Fred would be turning in his grave if he knew his family were turning their backs on the cause he died fighting for. In answer, Ron made it clear he believed Fred’s death was Harry’s fault, that they could have reached him in time to save him if the black-haired wizard had not slowed them down in the Room of Requirement trying to save Malfoy’s life. That nobody opposed that viewpoint told Harry and Hermione enough.