Update: 8 June - Did anyone attend D.T. Max's presentation at BEA?
He spoke about his upcoming biography about Wallace and revealed that the first time appearance of the phrase Every Love Story is a Ghost Story
is in a letter that Wallace ascribes to Virginia Woolf on the Merv Griffin show.
Update 18/5/12: Incorrect cover image happily removed per publisher's request.
Most intruiging aspect of the title? The line, "Every love story is a ghost story." can be found in §25 of The Pale King - one of my favourite sections - and in the story Tri-Stan: I Sold Sissee Nar to Ecko from Brief Interviews with Hideous Men.
(Thanks to Dan for the Amazon info and Noelia for the memory jog re: §25)