Religion

NI may have voted mostly Remain, but the contradictory requirements to have a border somewhere, not have a land border, and not have a sea border are going to be impossible to square. They know that Britain doesn't really want NI nearly as much as NI wants to be part of Britain, and the whole region is afraid of being caught in the middle with no real economy of its own. A referendum on leaving the UK and joining Ireland has been floated and frankly the question is more "when" than "if".

They feel, not entirely without reason, that their cultural identity is under attack from the ancient Irish enemy, backed by most of Europe, and their own countrymen would be willing to sacrifice them in the name of convenience. They're afraid, they're desperate,they're unwanted, and they're falling back on the time-honoured plan of scared, desperate, and unwanted people under threat: Do something stupid and hurtful!

They're still working toward attacking "the other" who actually looks like they do, dresses like they do, etc. But they'll get there. This is going to get worse before it gets better.