I think a reason that the EU is so well behaved is that the politicians know that they don't just compete with each other, they compete also with the non-existe

I think a reason that the EU is so well behaved is that the politicians know that they don't just compete with each other, they compete also with the non-existence of the EU. With time, as it entrenches and everyone believes in their hearts that the EU is going nowhere, then it will be less nice.