But, the loyalist factions were the majority, post WW2 it's just for sure that the UK wouldn't have (and certainly wouldn't now) hang around in Northern Ireland, apart from most of the people in Northern Ireland historically wanted to stay as part of the UK. A minority wanted to leave and fought a violent campaign to do so. The minority was ruthlessly discriminated against and terrorized by the majority - which complicated matters to say the least. These issues do not boil down in the way that you indicate, things are complicated. An agreement like the Belfast agreement had been on the table for the IRA for many years - and frankly it's not very favorable, the only major concession that I can think of was the dissolution of the RUC - but is the police service of northern ireland really that different? I mean it is vs the RUC of 1975 (that's for sure) but vs the RUC of 1998? The big issue that the IRA's final spurt of bombing decided was that they didn't disarm before the agreement was negotiated and signed - but instead after it was agreed and signed. The two truck bombs were painful, but Manchester would not be the city it is now without the last one - and docklands doesn't seem to have suffered much tbh. The Bishop's gate bomb in 1993 was probably more economically impactful than either, and there was no hint of compromise after that.
The UK has very limited economic, military or geographic interest in Northern Ireland. The oil was elsewhere, there is fishing - but we are talking $10M's per year at the most there, and most of that goes to NI boats in any case. There's no reason for the UK to be there apart from the fact that a) the bulk of the population think that they are part of the UK and b) the irish government would be in the mire trying to deal with it if it suddenly came to be their job. Without these two factors there wouldn't have been a conflict, because the UK would have dropped it like a hot coal.
NA had two minorities with opposite enough ideologies that they got violent. The UK would have never succeeded in keeping the peace there were it not for having a good chunk of the population on "their side". The violence eventually came to mostly an end because the IRA blew up enough crap that the British were willing to mostly throw them a bone in the Good Friday agreement and everyone was sick enough of the fighting to reach an agreement. The agreement was satisfactory enough for enough people that most combatants laid down their arms. An agreement so favorable (i.e. favorable enough to get them to stop fighting) to the republican faction(s) would never have been reached without the violence spilling over into England to a greater extent in the 1980s and making people ask tough questions like "why does what they do even matter to us?". You can call that a "loss" or a "win" or a "pivot to drug trafficking" or whatever you want to make it compatible with your politics. The framing doesn't really change what happened. Considering your characterization of North Ireland I don't expect you to frame the issue in a neutral way.
Consider how the troubles might have played out without loyalist factions. Starts looking a lot like some other, nastier, more resource sucking conflicts. Local support is required any time you want to make a bunch of people do stuff you don't want them to.