France has made it clear it will veto any EU-UK trade agreement that does not safeguard the livelihoods of those involved in the French fishing industry. The big sticking point for Germany is ensuring that British firms do not have unfair advantage over EU firms, for example via state subsidies.
Hardline Brexiteers do not want to see a deal as they are worried this would align the UK too closely to the EU. Equally, there are many people in the European Union who adjudge London to be extremely arrogant. This cohort does not want to see a deal as they'd rather look on as Britain faces the full consequences of Brexit.
Those consequences might include very restricted travel to the EU from the UK, from January the 1st, due to the 27-nation bloc's COVID-19 rules with respect to non members. British citizens living in the EU would likely face all sorts of bureaucracy. Then, of course, there are warnings of dire economic consequences for the UK, and possibly Scottish independence. We are told the key to securing a EU-UK future relationship agreement, to avoid chaos in January, is fairness.
Even in the absence of a trade deal with the UK, EU leaders know they already face many economic challenges. The prospects aren't looking good. As EU leaders continued their meeting in the Belgian capital, British Prime Minister Boris Johnson stated there is a "strong possibility" a trade deal will not be reached.