It's happened to all of us at one time or another - you witness a friend, colleague or loved one making a demonstrably bad decision, yet every time you try to rationalise with them, they stick their fingers in their ears and start humming to themselves until you walk away in exasperation.
Eventually, you have to accept they will indeed cut off their nose to spite their face and just let them get on with it.
Well, replace "friend, colleague or loved one" with the UK government and you get an idea of the awful yet avoidable predicament in which we now find ourselves, where it looks like the decisions made in Westminster are more a case of them cutting off their nose to spite our face.
This is the truly remarkable aspect of the whole fiasco - the main players in London still don't seem to have grasped the sheer enormity of the catastrophe they want to usher in.
We've gone far beyond the rights and wrongs of Brexit. The majority of the UK's voters chose to leave the EU. It was a tight result, but that's democracy.
After all, we only voted for divorce in this country by the wafer thin margin of 50.28pc to 49.72pc.
But there's a difference between supporting a political principle and wilfully engaging in the most egregious act of political self-mutilation of our lifetime.
As soon as the referendum was announced by David Cameron, the Irish gleefully hopped on the anti-Brit bandwagon.
Most of it was just silly or ill-informed but the underlying argument behind much of the sneering towards the English politicians seems to have been correct, even if for the wrong reasons - because it has become increasingly clear they just still don't get it.
The first sign there seemed to be a truly baffling disconnect between the pressing urgency of the issue and the weird twilight world of Westminster came on the last day before the parliament broke for Christmas.
Rather than trying to tie off any loose ends they could, or even set some sort of a sensible agenda for when they returned for the new year, they wasted the entire day obsessing over whether Jeremy Corbyn really said "stupid woman" about Theresa May.
It was a horrifying indication that too many of the UK's MPs are still treating Brexit as a party-political game rather than the most pressing issue any of them will ever have to deal with.
That lack of urgency and apparent inability to grasp the enormity of what is happening was best illustrated by Boris Johnson, who has decided to get into a bizarre war of words with Simon Coveney over who first suggested a land bridge between the Republic and Scotland. Who cares?
As Coveney, who seems to have developed the patience of a saint in recent months, was quick to point out: "There are 82 days to go to Brexit and we would not allow ourselves to get distracted by a bridge."
Speaking in advance of his appearance in Dublin on Thursday at a business seminar (it might have made more sense for him to stay in London to concentrate on his day job, but as we all know at this stage, Boris will do what Boris wants to do), Johnson then claimed: "The friendship and partnership between the UK and Ireland is so huge and growing... If we get Brexit right then I have no doubt we can not only protect that trade but watch it grow at pace." The simple response to that point is: How?
As we saw with yesterday's farcical scenes in Dover, when only 89 lorries turned up in a "war game" exercise on traffic delays that was meant to involve 150 lorries, they can't even organise a proper traffic jam. How can they ensure that trade between us and the UK will actually increase?
Leo Varadkar has been quick to point out that "good intentions are not enough" when it comes to the Border arrangement, but even good intentions are in short supply at the moment.
While it would be inaccurate to dismiss all Leave voters as Little Englanders, that unappealing trait has risen to the fore, with the flames gleefully stoked by the likes of Jacob Rees-Mogg.
For instance, it makes perfect sense for our Government to look for more EU funds to help soften the landing of a hard Brexit. Frankly, we would all be concerned if they weren't making inquiries.
Yet this eminently sensible contingency plan has been attacked by the Tory media, with the 'Daily Express' fulminating about the "Irish plan to beg for millions of euro to save their farmers and fishermen".
They seem to have forgotten that one of the main points of Brexit was to protect their own agriculture and fisheries industries and Rees-Mogg has been rousing the troops by saying: "If we leave without a deal, the main culprit will be the obdurate Irish Government's threats about the phantom Border issue."
That's the sign of a politician getting his excuses in early, while trying to distract his base form the real problem.
Frankly, it now suits the Tory grandee to, as they say, have a crack at the Mick.
What remains so baffling about this whole affair is not just the ignorance of the Tory political classes but the strangely antagonistic turn that matters have taken. As this whole process grows ever more farcical and inept, Leavers will be looking for a fall guy. It appears that's us.
Papers like the 'Express' and the 'Telegraph' never lost readers because they were too nice to the Irish, and Rees-Mogg has been doing his best to frame this as the old trope of plucky little Albion defending itself. But this is a Tory civil war with the rest of us left as collateral damage.
They voted to Leave out of their own self-interest. We want to secure the best deal possible post-Brexit out of our own self-interest.
Meanwhile, the EU wants to make an example of the UK because the whole European project is unravelling. There are now fears in Germany, of all places, of an AFD-led "Dexit", unless countries are given greater autonomy.
This means that it is in the EU's interests to make Brexit as difficult a transition as possible, 'pour encourager les autres'.
We have 11 weeks before the March 29 deadline, and things look even bleaker than they did last year, while May's plan for a rerun of the cancelled December vote next week is just an exercise in futility.
Hopes that someone would be able to pull a rabbit out of the hat have long faded, and while confusion amongst the electorate is understandable, the abject confusion of the politicians is a source of real concern.
Neither Johnson nor Rees Mogg are working class.
If they were, they might recognise the old football chant: "You don't know what you're doing."
Not only that, there's now a growing body of evidence that they don't care.