Do you agree with handing NI to Ireland, Gibraltar to Spain, Scotland to Scotland, Wales to Wales? What about Catalonia and Spain?
The only thing that matters is what the people of those countries/territories want.
Until then, the UK has a sovereign right and duty to protect its territory however it needs to and wherever it lies.
Rather bizarrely those with this point of view also believe that the UK should join in and integrate to become part of any future EU super-state...
I don't know that Scotland or Wales willingly joined the Union. Perhaps depending on your point of view. However they have been part of it and it's political structures for long enough.
I don't know your history with Spain and Gibraltar. I don't know what the will of the citizens there is but i would imagine they are comfortable being British. Does that ignore the will of the Spanish people on the other side of the border? I don't know enough, as I've said. So I'll stay out of that one.
NI was never a country however, until it became a British Conservative solution to both renege on the will of the island of Ireland which had voted for home rule and had it passed in Westminster and to appease the Ulster Unionists who threatened rivers of blood. There would have been an unmerciful civil war, with one side being heavily backed by Westminster.
As it turned out there was a civil war in the 26 counties as a fallout to accepting the British resolution.
The troubles in the North, didn't just happen in the 60s.
It was a direct result of British NI policy and letting social injustice happen as a policy.
Anyway. Overall I agree with your point of allowing the people themselves to decide their own fate. But in doing so just remember who created these arbitrary borders in the first place. Therefore, a great deal of thought goes into who the people that get a say, are.
Personally I wouldn't trust a Tory government to do anything right by the people of Ireland North or South.
They have a long history of nothing more than self interest. I think Conservative and Unionist party is a banner of convenience at times. Let's face it they'd hang NI out at the drop of a hat and I'd wager a large portion of England would too without batting an eyelid.
I've said all along you have a right to leave the EU. You voted to leave so you should.
But you should never have done so before first considering the implications for the citizens of The North.
If there were implications for your Union members that were not the same for all states/countries then that issue should have been sorted first.
If that meant complex difficult decisions regarding your own union. Tough.
For whether we like it or not here in the South. We are heavily involved through the GFA that we signed up for.
Regarding the joining of the EU super state. You have a choice whether you want to or not. It is not the same as the choice given us when we were part of the UK and it is not the same as the choice given to your empire colonies. when you had an empire.