Thank you, Merkel.

The stability (and even monotony) associated with German politics under Ms. Merkel appears to be coming to an end. Her looming retirement marks a deepening crisis of the German political system that threatens not just the future of the country, but of the European Union.

Explanations for this shake-up often begin and end with Ms. Merkel. Her handling of the so-called refugee crisis and her downbeat, aloof style alienated large chunks of the electorate. The gradual weakening of the centrist parties has in turn fed polarization and the fragmentation of the electorate.