Why does Winston regard OBrien as a friend even though OBrien is his torturer?

Winston views O'Brien as a friend due to the initial connection they share, which leads Winston to believe that O'Brien is a fellow dissenter against the Party. Their conversations and O'Brien's apparent understanding of Winston's thoughts create a sense of camaraderie and hope for rebellion. However, this perception is ultimately shattered when O'Brien reveals his true allegiance to the Party, illustrating the tragic irony of Winston's misplaced trust in someone who becomes his torturer.