Only the most sadistic of dinner party arrangers would ever choose to seat Jean-Claude Juncker and Theresa May at the same table -- so we shouldn't be too surprised that their Downing Street soirée last week was less than successful.
Theresa May: 'Let's do everything we can to make Brexit a success.'
Jean-Claude Juncker: 'There is no way it can be a success.'
And there, in one icy exchange, you have the heart of the problem. Mrs May has convinced herself that the UK can look forward to a glorious, prosperous future once it has left the EU -- if she gets the deal she wants. That's what she calls 'a success'.
Mr Juncker thinks the opposite: that Brexit will be a disaster for the UK. After all, what would be the point of the EU if member states could do better outside it than as members? To believe that such a thing is even possible would be to make a nonsense of the entire project.
On the morning after the Brexit referendum last June, I wrote: 'For the next several years, British politics will be dominated by endless negotiations, rows and crises over how to recalibrate our relationship with our neighbours.' It has started: the leak of the May-Juncker contretemps and Mrs May's Downing Street counter-blast were just the first in what will be a long, ugly parade of name-calling, spinning and leaking.
Why? Because name-calling, spinning and leaking feeds back into the negotiating process by putting pressure on the negotiators. If Brussels spins that the UK is being wholly unreasonable and that a so-called train crash Brexit is looking increasingly likely, that will have inevitable repercussions in Westminster.
Similarly, if the UK spins that because of Brussels intransigence, it is seriously examining the 'Singapore option' -- rock-bottom corporate taxes to attract investment away from the EU -- that will create pressure from, among others, German business leaders.
Remember what Philip Hammond said last January: 'I personally hope we will be able to remain in the mainstream of European economic and social thinking. But if we are forced to be something different, then we will have to become something different.' No one was left in any doubt as to what that 'something different' might be.
For Mrs May, the immediate priority is to stack up as large a majority as she can on 8 June. 'I've got my mandate, and I'll use it however I see fit.' Her opponents, both those in her own party and those on the opposition benches, will be expected to do little more than sit on the sidelines and complain impotently.
Her Downing Street counter-blast on Wednesday was aimed squarely at British voters, not at Brussels. Look how tough she is, look how she can give as good as she gets. Can you imagine Jeremy Corbyn or Tim Farron being this tough? And who needs UKIP now? (On that front at least, the early results from Thursday's local elections seem to have clearly vindicated her Boudicca act.)
The tragedy is that the gulf between Brussels and London is, as it has always been, as much cultural as political. Mrs May's and Mr Juncker's generation simply see the world differently -- the under 30s, who will have to live with the consequences of the decisions made in their name, tend to be far more understanding of each other's cultures and societies.
For the Brexiteers, walking away from the EU is a rational decision based on what they perceive to be in the UK's best interests. For many in the EU27, it's far more than that -- it's an irrational and incomprehensible repudiation of their very identity as Europeans.
That's why the negotiations will be so ill-tempered. You can't negotiate over identity. And that's why, for the next two years, the UK and the EU27 are going to say some very nasty things about each other.
How will it end? Let's hope for the best and plan for the worst. Just in case.