It seems to me that a large part of what Europe is suffering from is strongly akin to immune system problems.
One can view patriotism as a form of immune system for a society. Patriotism creates, at the level of a society, a sense of “self” and acts to both maintain that self and protect it from “other”. Although many EUlite would deny it, some level of patriotism is necessary for the continuation of the society. If there is no positive, emotional feelings for the society by its members, the society is doomed in the long run either from internal collapse or conquest by another society, just as a biological creature without an immune system will fall to internal decay or opportunistic infection.
However, just like an immune system it’s possible to have an overactive one. Societies can have too much patriotism, in which case we call it jingoism. The dividing line in my opinion is where love of country starts to be replaced by hatred of others.
The problem in Europe seems to be a calibration problem, in which the leadership seems to be either jingoistic or apathetic. After the disasters of the first half of the 20th century, the EUlite seem to have decided that it’s better to not have any patriotism than the kind they had then.
I’m not sure why the USA has avoided this problem, but I suspect that it’s because America is an idea, not blood or soil. This means that immigrants (although having a rough time of it) can eventually become just as American as any other citizen. Moreover, America is a high idea, not a small one. For instance, it’s more religious than any particular sect. It’s about cooperation, not some particular organization. It’s about having friends, not about the “right” friends. It’s about a self ordered society, not a particular political party. Because of this, America can aborb the quotidian details of immigrants (like salsa instead of ketchup) while preserving the true essence of America.