Theresa May, according to ITV News' Robert Peston, has dispatched her chief whip, Gavin Williamson, to Belfast in the hope of negotiating a formal coalition with the DUP. Of all her rash and shortsighted moves on Northern Ireland, this is by some distance the most ridiculous.

Why? Because, as the DUP themselves have made abundantly and repeatedly clear, they have no interest in entering into a formal, full-blown coalition. Nigel Dodds said so in 2015, when the six months before the election were dominated by talk of how David Cameron and Ed Miliband would cobble together a commons majority.

I am reliably told the same is true now. Entering into a formal coalition would reduce the party's substantial leverage over the government. They have no interest in doing so. The eight DUP MPs in the last parliament were very useful indeed to a government hobbled by a slim majority. The 10 in this one are essential to its slim chances of surviving. While some codified deal is possible, it is unlikely to be a coalition as popularly understood.

Nor do they want to be shackled formally to a prime minister who, as Arlene Foster is concerned, is more or less finished. The DUP leader said yesterday that it would be "difficult" for May to survive such a disappointing election result. As the best-practiced bargain drivers in the commons, her party will not want to be contractually obliged to act as a doomed May's life support machine. If they wouldn't do it for Cameron, they certainly wouldn't do it for his irredeemably tarnished successor.

Then there are the politics of Northern Ireland itself. Mainland commentators have seemed to suggest with various degrees of sincerity – and, indeed, familiarity with objective reality – that the DUP would be willing to tear up Northern Ireland's post-Troubles settlement for the sake of some pork barrel spending and, even more implausibly, a state attack on women's and LGBT rights across the UK. (The 1967 Abortion Act does not apply in Northern Ireland, and the DUP oppose its extension to the province, as is the case with equal marriage legislation).

This, to put it plainly, is nonsense. While the DUP's approach to the devolved institutions has often left much to be desired, there is no reason to disbelieve its politicians when they say they would like to see a devolved executive restored, even if their terms for restoration are unacceptable to Sinn Fein.

Despite the sectarian posturing that is inherent to Northern Irish politics, there is, in 2017, one fundamental point of consensus. And that, in the words of one DUP MP, is that the Troubles – and the long years of direct rule – were "crap". The unionists want a good deal but not at any cost. Nobody has any interest in Northern Ireland becoming an ungovernable basket case again (not least the parties that get to run it), which is what May risks by attempting to broker a deal with the DUP which goes way beyond the backroom schmoozing of the last parliament.

Nor does the DUP, which has played its hand well in the months following the collapse of the executive, want to look in any way culpable for anything that further exacerbates the impasse. That is why, unlike the Prime Minister, they have been very careful indeed not to commit publicly to anything specific. And that is why Theresa May is wasting her time seeking a formal coalition.