I can’t say that I understand Irish issues well enough to render an informed opinion.
Wouldn’t a fairer question to submit to the polls be:
Option one: Northern Ireland unite with the Irish Republic as an independent country
Option two: Northern Ireland unite with the Irish Republic under British rule
Option 3: Leave it alone as it is.
Northern Ireland is mostly Protestant, while the rest of Ireland is not only mainly Catholic...but Irish Catholic. Now the strong religious factions are breaking down so a united Ireland is possible IMO. The real hatred of each other’s religion began with William and Mary of Orange when they took the throne and legislated against just the Irish Catholics, forbidding them owning land, forbidding the Church holding mass, etc. Feelings run deep and it has taken centuries to get over...but religion seems to be a failing enterprise nowadays so perhaps everyone can live in harmony.
Better it come about peacefully, like this. Northern Ireland exists separately from the rest of Ireland because of threats made by Protestants, including one lord, regarding terrorism against the other Irish if the British government didn’t ignore the result of the island-wide referendum to be independent from Britain.