I don't think anyone is telling them that: in fact their concerns are absurdly well catered for, though you wouldn't know it listening to the constant complaints.

We can split hairs about what is and is not democratic until the end of time, but the debate takes place in a historical vacuum: the creation of Northern Ireland was a response to a very specific set of circumstances, and I don't think yak-shaving about democratic niceties casts any light.

It is moot anyway, because there is no prospect of changing Northern Ireland's status without democratic sanction. Which vote of course takes place at the pleasure of His Majesty's Secretary of State for Northern Ireland.

It is not quite at the pleasure of His Majesty's Secretary of State for Northern Ireland. It is defined in law that if there are grounds to believe it would pass they would be required to hold a border poll. This could be decided in court, as in if say opinion polling was at 70% and nationalist parts were winning 70% of the votes, and the Secretary of State refused to hold the poll. They could be brought to court and a judge could rule the secretary has no grounds to refuse.