If you think about it, Brexit is really a secession of sorts. The UK, within the EU as currently constituted, is much like a State within the Republic of the United States, with an important difference that they have no real Constitution, as far as I know, and certainly no bill of rights.
No reasonable person, it seems to me, could or should accept being ruled so absolutely by others so far away.
I think World War 2 really was the war to end all large European wars. If there is another one, it will be a civil war waged against the EU apparatus itself.