I guess there was no PRENUP when the European Countries formed a Union. They expected it to last forever I guess. How trustworthy are unions between people, among countries? Why?

The problem with the EU is that it went from a free trade zone agreement initially, but then started to expand into a political union.. There was forces in the EU bureaucracy that are trying to create a United states of Europe in a thousand small steps without the approval of the ordinary people of Europe.. The EU was slowly but surely undermining the authority of the national governments of Europe and their parliaments where becoming rubber stamps or being restricted by Brussels EU laws..  They tried to boil the frog of nationalism by slowly increasing the temperature.. But the frogs noticed what was happening and the UK frog is the first to jump out of that pot... Other frogs will be following i am sure..