Just remind everyone here
a) there is a legal and structured framework ALREADY in place that would allow for the unification of Norther Ireland with Ireland as part of the Belfast Agreement. It is democratic and can take place at any when the conditions are there as specified in the treaty (i.e. majority view of the need to have the vote etc). This agreement is under international treaty.
b) Scotland has a vote for independence in Sept 2014 They decided to remain in the Union. Once there is sufficient and sustained consensus in Scotland, then another vote can take place, but it is something that can be requested to be done "every year" like some football game. But, the democratic framework is there.
c) So far to date, Wales has not made any real or significant ask for Independence from the UK. Yes, some "Nationalist Leaders" have said this, but so do people in Texas, right ? These "Nationalist Leaders" have to demonstrate there is sufficient grounds for a vote and the framework is there, and the will to hold those elections (eg Scotland is there).
How many other countries are so "free" with providing people with the right of self-determination to decide if they want to stay in the country, or leave ?
The Union is of consent and it has demonstrated the will to hold the freedom of self determination at is core as demonstrated to date.