The Germans have a term for what holds them together: Wehrhafte Demokratie. It roughly translates as fortified democracy, but that does not fully render its meaning. In essence, it refers to the idea that the state has the right to act against those who threaten the liberal democratic order.
Another guarantor of German stability was the postwar constitutional settlement that founded three Volksparteien, big-tent “citizens’ parties” operating along carefully regulated parameters, encompassing centre-left, centre and centre-right. None would enjoy absolute power, which required coalitions, compromise and consensus at national and regional levels. As a further safety net, parties with less than 5% of the vote couldn’t join parliament, excluding fringe groups.