As far as I could tell, the [Brexit](https://en.wikipedia.org/wiki/Brexit) issue boils down to three core points for the UK:

1. The UK no longer has to follow any EU regulations.
2. The border between Northern Ireland and the Republic of Ireland remains without customs/border checks etc.
3. There will be no kind of "customs/border-like-checks" between Northern Ireland and the rest of the UK.

Given that the EU common market (among other things) enables forgoing border/customs checks by ensuring all members follow the same standards (and the UK does **NOT** want to be bound by those standards), I have a hard time imagining how those three points are supposed to achieved at once.

Otherwise, if e.g. pineapples were to be made illegal in the EU but not the UK (or vice versa) trucks full of pineapples would be able to (freely) move from the UK to the EU (or back) without being detected (since there are no border checks) – and the side that made pineapples illegal probably doesn't want that.

So, let's just pretend the UK would be able to convince the EU of its ideal version of the Brexit deal (excluding the EU dissolving or similar nonsense) – what would it look like? What solution did the UK provide which the EU was unwilling to accept?