A correction (late night thinking is not my forte).
Isolationism: "the sense that our own problems are so overwhelming" belongs more to De-Solidarization. Isolationism springs from the belief that 'we could do so well without the shackles of the rest of the world.' You can see that phenomenon playing out between West Germany and East Germany: 'When are we gonna stop transferring billions to that depopulating area every year?', and between states/Länder regarding the Länderfinanzausgleich (tax revenue transfer between wealthier and poorer states). Bavaria and Baden-Württemberg are especially keen on getting out. The new Green-Red coalition (!) in BW wants to sue before the constitutional court.

_{Schengen is toast!}