Why Brexit will force Ireland to leave the EU, also Scotland, N.Ireland and Wales.

Ireland has been in partnership with Great Britain since 1800, the Act of Union 1801. Similar act of union between the other countries exist.
Many in Ireland have no clue as to why Ireland and England are still connected, it seems most in England do.
The English seem to realise, if two countries are in a Union (Ireland is subordinate) and then later the dominate country gives the subordinate country Home Rule (1922, not a republic), then the dominate country adds the Statute of Westminster 1931. Things can happen.
Said subordinate country can create its own rules for governance and legally remove Acts and Statutes from the statute books that had been created by the dominate country. This can all work but only within its (subordinate country) own borders. It can not be recognised by the rest of the world.
That being said, the subordinate country can not undo what it did not create. If the dominate country removes the Act of Westminster, the subordinate country is back to square one.
Ireland is only a Republic is statute, which means it is NOT recognised as a Republic outside of its own borders.
Even the type of Republic it claims to be is not defined, it's just a name.
Ireland had a rebellion in 1916, it failed. The long fought for Republic was eventually traded for home rule in 1922 with the creation of the free state. The government of Ireland (which is an act of parliament 1920, Westminster) later used the Statute of Westminster to create a new Constitution named the Constitution of Ireland (note it does not claim to be a Republic). They removed any reference to the King and the Governor General, named Ireland as sovereign, independent and a democratic state in article 5. It also gave its citizens rights under article 40.
What the politicians, Law society and upper Civil Service did next was abhorrent , they inserted article 6 and it is as follows:
Article 6

1. All powers of government, legislative, executive and judicial, derive, under God, from the people, whose right it is to designate the rulers of the State and, in final appeal, to decide all questions of national policy, according to the requirements of the common good.

2. These powers of government are exercisable only by or on the authority of the organs of State established by this Constitution.

What this means is the People do not elect representatives but RULERS. That is not the worst part, then the government claim a final say in EVERYTHING, that's right EVERYTHING.
The Irish People have no rights, no private property, nothing! They are legally slaves, by there own hand.

Now, the only way they can undo this is by de-registering as they enacted this constitution. They must reach 51% to revert back to the old free state constitution or call for a new constitution.

Sadly, neither will happen as the Irish have no idea what is going on. Sad but true.