I think the UK has a problem with being an equal and has not got over its loss of empire, just look at how they treat their own constituent countries such as Scotland, Northern Ireland and Wales
To be fair: whatever us Germans and the French want, we eventually get - most often by outright nation-scale bribery. It's all backroom dealing - for example, us Germans get no opposition preventing harsher pollution regimes EU-wide (to protect our heavy car-oriented industry), the countries which would oppose get EU funding grants for construction or whatever.
Don't forget England. Brexit is basically just an English nationalist idea. Ironically, if the UK had devolved more powers to Scotland, Wales and Northern Ireland (something the Westminster parliament has generally fought against), England might have found its own thirst for taking back control satiated.
1. Irish border and Good Friday agreement
2. EU Citizens rights in UK
3. Payment of billions to which previous UK governments signed up to as EU member
4. How will you ensure low quality food from US does not enter EU"
Just like Russia could say "no gas for you" if you make too much of a fuss about what happened in Crimea.
Now if the UK's view of its own future diverges from the EU, it's totally normal to see complications appear during negotiations.
Canada had to adjust their immigration policy for several EU countries to get CETA. The UK will be over a barrel and will have to make major concessions.
Whether you're pro EU or not this situation is a total balls-up.
Hard to imagine a good outcome.