Nationalists caused the Partition of Ireland. In the 1840s Home Rule was mooted. At that time unionists called for Ulster to be partitioned from the rest of Ireland if Home Rule passed.
The Home Rule Party agreed to Partition with great reluctance in 1914. They intended it to be temporary. Sinn Fein agreed to it in 1921 at the Treaty. Dail Eireann ratified that in 1922 and an election upheld the result. Nationalists caused Partition. There would have been no Partition without secession. Even if all of Ireland had left the UK there would still have been a Partition. It would have been a division in the British Isles.
It was moronic to leave the UK when we did almost all our trade with the British Empire. SO many of our people found work in GB or the dominions and colonies.
Now Brexit has brought the border issue to the fore. The United Kingdom is absolutely entitled to leave the UK as specified in the Treaty of Lisbon.
Clissaire shows her anglophobia. She wants NI to leave the UK and join the Republic. Fair enough. She wants Scotland to leave the UK. Again it is a reasonable opinion. She then said she wants England and Wales to go down in flames. She says other states should not help as the ENglish and Welsh have caused this. This vitiates the sympathy she said she feels for the Remain voters.