They haven’t been sold out. As a Mancunian i may or may not want to be in a union but it’s none of my business whether a Scotsman does or an Irishman does. I don’t live there so cannot make that decision or give an opinion on their behalf.
Unless I’m wrong NI is still part of the Union. They are specific things that apply to NI because of a complicated history that isn’t worth going over. But nobody decided to vote the way they did because they are unmoved by the people of Northern Ireland. Just like the Irish didn’t vote taking into account English folk. It works both ways. You ask everyone the same question and see what the result is.
So much hassle is caused by people labelling themselves and being bothered about which govt shafts them. Tub thumping nationalists or unionists obsessed with lines on maps need to grow up. That applies to everywhere in the world.
If you have self determination in a democracy then use it and decide what is best for you and your countrymen going forward.
If we take the 4 countries of the U.K. and let’s throw in Southern Ireland as well for giggles there is lots of permutations there. Total independence a Union of all those countries, some of those countries, Eu membership. It’s 2020 grow up, make your mind up and get on with it.