There is only one reason for the rise of nationalism in EU. It is EU itself.
The reason why Soviet Union, another international power structure forced down on peoples throats collapsed was the same reason why European Union, another international power structure, will collapse. People don't like it. It is that simple. A guy in finnish Lapland does not like when a spanish EU bureaucrat tells him what to do. A guy in Spain really does not like when a finnish eurocrat tells him what to do. People do not want to be ordered around by foreigners. It is natural reaction. There was a small war called WW2 which basically was about Germany wanting to tell everybody else what they should do and the rest opposing them. People remember that.
People in the east remember how it used to be when the orders came from Moscow and the local satraps skipped and hopped at command. This is happening in EU too right now. Orders come from Brussels and people are expected to obey no matter how stupid or ridicilous those orders are, how far removed from the realities they are.
One glaring and good example are those energy efficency directives the EU has given. An EU directive is an EU law and overdrives any national laws it touches. These energy efficency ordesr make sure that all new houses built in Finland will be so called mould houses, that they will become in few years unhabitable due to the humidity which will gather inside the structures. This happens because of our weather. It can be plus 15 celsius degrees at day time and minus 15 the very next night. Traditional finnish log houses stood on short stilts allowing the air circulate under the house keeping it dry and off the ground. No wonder the EU wants to deny that way of building houses because "it is not energy efficent".
All the power structures which rule over more than one cultural group have been forced ones. International rule has always been forced on people trough violence and force. This was true for centuries in Europe when the nobility and royals ruled over vast areas all across the continent and fought wars against anyone and everyone. Napoleon created his empire via war, so did Sweden in 1600's, so did Russia, Spain had done it before, various German empires the same etcetcetc.
So, US Europe is not nor it will never be. What about the so much touted democratic EU? It is complete sham. There is nothing democratic in EU. The whole system is designed to take away the ability of the people to influence on their own matters. The eurocracy is designed to rule over the people for the EU itself, not EU for the people. The eurocrats are hired by EU and not by any democratic process. The Comission is not chosen by the people and it is not answerable for the people. It just rules the people for... For whom? That is the question.
As for the "democratic heart of EU", the so-called europarliament, it is a ridicilous theater of anti democracy posing as an democratic institution. The MEPs do not represent any people who vote for them. They don't even represent the parties whose candidates they are in their home countries during the euroelections. They do not represent their own countries at all. They belong to the artificial europarlamentary groups which do not represent the people or nations but the EU itself. That is a travesty. That is not democratic in any way.
People have seen the power slide further and further away from them. If they felt long ago that the people in national parliaments were out of tune of their lives and far removed from the lives of ordinary people, what about now? Those MEPs at Strasbourg and Brussels are thousands of miles away from their lives. They are from countries thousands of miles away.
They have never been in my country and have never lived my life, and yet, there they are thousands of miles away deciding how I must live my life? I never voted them in any election. I have never given them a permit to make those desicions about my life and now I must obey their desicions?
This is how ordinary people around Europe, under the rule of this distant artificial international power structure called EU, think. This is how they feel. They feel this is not right. This is not fair. This is not democratic.
Many european nations and people have a long history of resisting foreign invaders and attackers of all sorts. Many of them fought long and hard wars to maintain their independence and self determination, even their right to exist under the oppression of the old international empires. Now they are all expected to give all that up without any whimper or resistance?
Who ever believed that was dreaming. You can not wipe out the history of the people of Europe. You can not pretend that there are no nations in Europe. And yet, this is what we are asked to do by the super international power structure of the EU.
This is why the EU will collapse. It is not the project of the people, by the people for the people. It is a power structure created by a small elite group of business world and politics. It is supported by the old ghosts of the european empires of yesterday. Those power structures were over thrown by the very same people now asked to become underlings of this new empire. And some wonder why people resist, why the nationalism is on the rise?
For sure, the neo nazis, racists, xenophobics and others try to take their chance with the feel of the people. They try to cash in, use the mood for their advantage, but they have not created this rising tide of national pride, the surge of local identity and longing for the cultural cohesion and unity among ones own people.
The European Union has created this longing with its lies and faking. The EU has waken up the nationalism and it will break up because of it.