Can Americans still have a sensible and friendly political discussion across the partisan divide? The answer is yes, and we prove it every week. Julie Roginsky, a Democrat, and Mike DuHaime, a Republican serving as a senior advisor to Chris Christie’s presidential campaign, are consultants who have worked on opposite teams for their entire careers yet have remained friends throughout. Here, they discuss the week’s events with editorial page editor Tom Moran. Q. Let’s start with Chris Christie’s surprise decision to quit the race. Did he really think he might win? Or was this a patriotic kamika…