Well, I dated 10 "2010" on purpose -- I think it's not unlikely that Jack didn't open up to Ianto as much as he could have, pre-CoE, in part because if he tells Ianto every horrible thing that ever happened to him he's going to be talking for a LONG time. :D So I think given more time Jack might start to tell more stories, but it would need that emotional kick of Tosh and Owen dying, and a deepening relationship, before he could.