"Actually, that's a rather lame reason"
Exactly. If a majority of this countries citizen's want to annex Canada, well, why not? Or if a majority of Mexicans want their country to absorb the next country north on its same land mass, surely they should be permitted to do so.
It stands to reason. Lame or not.
NI is an artificial construct. Ireland was historically one country with 4 provinces. When they split it up they couldn't even find a majority of loyalists in 1 province so they had to divide that as well.
I suppose it's all a moot point though because within 2 generations or so there will be a catholic majority in NI and reunification will be a sure thing.