There are countless things that hold unhappy countries, like marriages, together — shared history, shared wars, shared children, shared enemies. But the economic crisis in the European Union is also highlighting old grievances.

Many in Catalonia and Flanders, for example, argue that they pay significantly more into the national treasury than they receive, even as national governments cut public services. In this sense, the regional argument is the euro zone argument writ small, as richer northern countries like Germany, Finland and Austria complain that their comparative wealth and success are being drained to keep countries like Greece, Portugal and Spain afloat.

The crisis has also produced a loss of confidence in traditional leadership, with voters punishing incumbents and mainstream political parties. That has helped more atavistic nationalist parties, like the National Front in France and Golden Dawn in Greece. But in separatist regions, the same disaffection tends to favor parties advocating independence.

“The whole development of European integration has lowered the stakes for separation, because the entities that emerge know they don’t have to be fully autonomous and free-standing,” said Mark Leonard, the director of the European Council on Foreign Relations. “They know they’ll have access to a market of 500 million people and some of the protections of the E.U.”