Trump and Li'l Kim show how it's done.

From the BBC:

A summit between Donald Trump and the North Korean leader Kim Jong-un ended without agreement after the US refused North Korean demands for sanctions relief, the US president has said.

Yup, both sides make demands unacceptable to the other, that's it, call the whole thing off, no hard feelings and better luck next time.

Trump and Li'l Kim have thereby achieved more in two-and-a-half days than the EU and Theresa May have achieved in two-and-a-half years of grinding pettiness, without all the associated loss of goodwill.