Did Jackie Kennedy have an affair with Robert Kennedy?

Well nothing has been confirmed on that yet, although there are plenty of rumours out there that she did. In the book 'America's Queen', the author plainly states that there was some kind of romantic affair going on between Jackie and Bobby and many other books have also taken the same stance. However, there does not appear to be a unanimous acceptance that they embarked on a sexual affair with many authors arguing that it was purely unconsumated. It seems that Ethel belived that they were 'at it' though. Also a recent book by C. David Heymann, Bobby and Jackie: A Love Story makes this charge forcefully.