To me the most difficult issue during all this.process will be Northern Ireland. Some politicians in the UK are trying to show us that they will find a solution such that you can have A=B, B=C but A different from C ! This single issue will be the one impossible to solve and will frustrate brexiters goals. At the end we will either keep such a strong link between UK and EU that the Northern Ireland border remains will remain invisible, or we will put borders and controls between the 2 while allowing NI to be giant loophole in the system
So I've presumed the government's plan was to commit to NI always being regulatorily aligned with the EU, and whilst they have to, to assure DUP that there'll be no border between GB and NI (which there needn't be, whilst we remain regulatorily aligned ourselves) - except there will be eventually. Once they're no longer reliant on DUP's votes - and that way she can keep all sets of hardliners onboard until we've left the EU and can then safely collapse the government knowing even if a fervently pro-EU party got elected they'd need to rejoin on terms the British public are unlikely to sanction.
Only today Barnier/the EU have thrown an enormous spanner in the works on that: by enshrining the sea border into law there is no way the DUP position that there is to be no divergence between the NI & GB can now be satisfied. I have no idea why the EU have done this, when it's probably the only workable solution going - unless they're hoping for a softer Brexit and doing this to try to collapse the government?
The EU has only proposed what Theresa May offered it in December.
