Found it in an interview he did:
Mostly, Cave and his wife, Susie Bick, who also appears in the film, talk around Arthur rather than about him: It seems they’re balanced on a thread between heightened awareness and permanent numbness. Cave speaks somberly about his inability to think, let alone talk, about the days around the time Arthur died. “Time is elastic,” he says, “We can go away from the event but at some point the elastic snaps back and we always come back to it.” At one point Dominik’s lens scrutinizes Cave’s face, currently that of a tired, ancient boy, as if he were showing it to us for the first time. In fact, it’s as if Cave is seeing it for the first time. “What happened to my face?” he says. “Look at these bags under my eyes. Where did they come from? They weren’t here last year.”