"About five years," Frodo said with the ease of someone who had worked very hard to accept such a fate that it was almost natural that he a) didn't give an exact date, and b) didn't immediately think the question odd. His simplicity was outstanding, and he'd always been very naive. "But what does that have to do with it?"
It was more surprising to him that he'd figured out the part about the girlfriend. It was a new development. So new, that Frodo himself got caught up thinking it.