I'm old enough to remember when the UK joined the European Economic Community, which means I'm old enough to have seen the transition from a trading relationship involving a few countries to an ever-growing Economic Community (EC), and now to a European Union embracing a flag, parliament, anthem, president, central bureaucracy, burgeoning integration, single currency and the beginnings of a joint foreign policy and army.
A direction of travel we were assured in 1972/3 would never happen. That is why I voted Leave in 1975. And that is why I voted Leave in 2016. I don't regret either of those votes.
During the 2016 referendum (and I wasn't part of any of the pro-Leave campaigns) I acknowledged that, in the event of a Leave victory, a bespoke arrangement would be required to deal with the unique circumstances of Northern Ireland.
I had no difficulty with that. NI has been a 'place apart' since partition (unionists have forgotten that the Stormont Parliament made NI significantly different from the rest of the UK in political and constitutional terms), and even without Brexit, would have continued to be different.
Anyway, in August 2016 Arlene Foster and Martin McGuinness wrote a joint letter to new PM Theresa May setting out an agreed game plan: "This is too big, too serious for us not to be joined up in relation to how we take this process forward.
"This is about how we protect the interests of the people we represent and the challenges that lie ahead... We have had constructive initial discussions with the Irish Government through the NSMC and wish to play our part in the engagement between the two Governments on the unique aspects of negotiations that arise from the border, recognising the possibility that it cannot be guaranteed that outcomes that suit our common interests are ultimately deliverable."
All of that made sense to me. Sadly, from December 2016 onwards everything went downhill and the relationship between the DUP and Sinn Fein became more toxic than it had ever been.
The 'confidence and supply' arrangement between the DUP and Conservatives in June 2017 opened the door to an improvement in the relationship re dealing with Brexit. Yet for reasons which have never been entirely clear, the DUP went into full-blown uber-unionist mode, moving increasingly close to the ERG's worldview of the EU and not bothering to work hand-in-hand with those prioritising the bespoke approach of August 2016.
I remember writing a piece warning the DUP not to throw all of its eggs into the ERG basket, then a later piece when I warned it not to trust Boris Johnson at all. But the DUP was listening to nobody. It believed it was calling the shots.
I think it also believed that parliamentary tactics by others and another bad election for the Conservatives would combine to kill off Brexit once and for all.
As we now know, the party overplayed its negotiating hand, overestimated its importance to the ERG and pro-Brexit Conservatism generally, and allowed itself to be serially and spectacularly shafted by Johnson and Dominic Cummings.
The DUP has nothing to celebrate today. Two years at the top table of Government didn't deliver even a few crumbs of face-saving comfort. I'm not persuaded that this is an existential moment for the future of the Union, by the way (a future which will be decided by the entire electorate of NI), but it is an existential moment for the future, shape, nature and strategy of party-political unionism.
If it doesn't learn the key lessons of the past three years and rethink the terms of the relationship between NI unionism and broader GB unionism, then it will be screwed.
The transition phase will allow for a calming of nerves, acceptance of realities and building of certainties, which will, I think, improve the relationship between London and Dublin.
The rebooting of the Executive - albeit still fraught with older unresolved difficulties - should help the London/Belfast, Belfast/Dublin relationship (the relationship between the DUP and Varadkar has been particularly poor since December 2017, with many in broader unionism also accusing him of playing the 'England's difficulty is Ireland's opportunity' card).
But the key test in the next year will be for the DUP. It has a pretty unappetising deal to sell to all of unionism, as well as to some elements of small 'n' nationalism, and it must avoid arrogance, stupid pledges and pointless standoffs. NI unionism is in an extraordinarily difficult position right now. The DUP's only task is to do nothing which adds to that difficulty.