Comment by Yizahi

That is incorrect. Leaving EU is super easy. Leaving written accords with USA is hard, and that's what UK tried to pull off. Since the oligarchs pushing for EU exit to hide their black money were dumb, they forgot they have an agreement with USA making a UK-Ireland border transparent. And they basically spent 4 years trying to either tear down a USA deal or EU law, without having any leverage for either, since they are dumb. Since there no such things in other EU countries, their leave can happen much faster.