Half my ancestry is from Northern Ireland, my cousin has written on the history of Ulster, and I remember the start of the Troubles there, when the Catholic/Sinn Fein movement seemed in tune with the student movements in France and Germany, not to mention our civil rights movement.
Bottom line--I've tracked developments there with more interest than elsewhere in Europe or the world for that matter. To me it's an object lesson in human nature, a lesson to put alongside the lesson from Israel/Palestine and the various racial and ethnic conflicts here and abroad. People are able to discern differences in fine distinctions and often use them as the basis for enmity. Such patterns tend to endure through time, and often lead to vicious cycles of eye for an eye.
(Watch the TV series Fauda for another example of the same.)
Here's the Times on the current status. It also seems that there's a cycle at work--the young get riled up, get violent, get exhausted, and there's less violence for a while until a new generation comes along.