After years of squabbling, Harry Potter's best friends Ron Weasley and Hermione Granger finally became an item -- but now their creator JK Rowling has admitted she made a mistake by marrying them off.

Hermione -- whose quick wits get the teen wizards out of many a scrape in Rowling's hit novels -- would have been better off with hero Harry, the British author said in comments published by the Sunday Times newspaper.

In fact, Ron and Hermione would likely have ended up in marriage counselling, Rowling suggested.

"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," Rowling says in an interview with Wonderland magazine, previewed by the Sunday Times and due out next Friday.

"I know, I'm sorry, I can hear the rage and fury it might cause some fans, but if I'm absolutely honest, distance has given me perspective on that. It was a choice I made for very personal reasons, not for reasons of credibility.

"Am I breaking people's hearts by saying this? I hope not."

Rowling's interviewer in Wonderland was none other than British actress Emma Watson, who played Hermione in the blockbuster movie series based on the Potter books.

The actress agreed with Rowling, saying: "I think there are fans out there who know that too and who wonder whether Ron would have really been able to make her happy."

Rowling has sold more than 450 million copies of the Harry Potter books, which were made into eight films starring Daniel Radcliffe, Watson and Rupert Grint as Ron.

The franchise has made Rowling an estimated fortune of £560 million ($920 million, 683 million euros), according to the Sunday Times' Rich List 2013.