As noted in the Latin American thread; you have elites in one part of the world who never quite grasped sharing power, privilege and wealth sufficiently to bring their economies and nations fully into the family of developed world nations; While in Europe and the U.S. (and here if we're not careful) you have elites who want to roll back many of things that brought such wealth to their nations.
Fomenting nationalism is at odds w/the European project.
But at the same time, the E-U. has been more focused on liberalized trade and free flows of capital than on protecting the middle/working class and raising standards of living for a generation.
They were never honest with (themselves?) or Southern/Eastern Europe about the scale/scope of change required of nations in an integrated Europe and the impacts of internal migration and economic modernization.
Rather than insist ( support) less well off nations/areas in coming to terms w/the change, they've allowed, if not promoted mass internal migration as the way of dealing w/it.
This has exacerbated social tensions, rather than easing them.
I see nothing w/one Europe in the medium and longer term, less tribalism would be a good thing. But for a continent rife with a history of revolutions, their memories seem all too short. Radical change breeds backlash.
Further, since enshrining the E-U. minimum of 4 weeks paid vacation, there's been little move to upward harmonize either labour standards or social spending.
Indeed, if anything, there's been downward pressure, particularly on pensions. The latter is understandable giving an aging, but increasingly long-lived population.
But its the absence of a cushion in some places (Greece) and the absence of an obvious long-term benefit in others {France) that are putting enormous strains on Europe.
We again need to be aware of this here. We're in a comparatively better position as a country than many; but self-satisfaction will not help that. There are social fishers in need of addressing, sooner, rather than later.