The EU won't negotiate a reasonable Brexit deal with the UK because it does not want a reasonable Brexit deal with the UK.
The EU wants no Brexit deal at all.
Rather, the EU wants the fall of Britain's Brexit-bound Johnson Government and its replacement by a Lib-Lab-Green-Marxist-Whatever Remain Government for the greater provision of cushy Euro-bureaucratic jobs and other payoffs to Europhiliac politicians and bureaucrats.
Trouble for the EU is that blocking a reasonable Brexit deal validates Boris Johnson's claim to represent the Britain's national interest in a conflict with the knavish tricks of the imperialistic European Union.
It's a case of heads the UK wins, tails the EU loses.