Having reached a deal with the EU, Boris Johnson's task is now to find a majority in the House of Commons. This is complicated by the rejection of the deal by the DUP. There is also a serious question whether the Prime Minister can convince not only the MPs supporting his government but also the Conservative rebels and a sufficient number of the opposition.
One of the issues is the Benn Act. Having the possibility to avoid a no-deal situation by another extension might tempt many MPs to vote against a deal that will contain a range of difficult provisions, as well as providing a tempting opportunity to defeat Johnson yet again.
What is the rational response from an EU27 perspective? One is to wait and see what the House of Commons decides and, if it be no deal, hold out for the letter requesting an extension, hoping that, in the end, the political processes in the UK will lead to a second referendum that returns a remain majority.