The majority of NI wants to remain part of the UK - for economic reasons mainly and patriotic. Most of the industry was concentrated up there too.
The negociations were done in secret at first by John Major. For years the line had been "We don't negociate with terrorists", as had been proved over and over (the Iranian Embassy attack by the SAS being a good example). It seemed like the killing would never end. Everyone was tired of it. By reaching out to the moderates, you take away the support for the extremist nut-jobs. Compromise was the key.
The road has not been smooth. The Real IRA, essentially the hardcore elements of the group, refused to accept the IRA ceasefire and continued murdering. This culminated in the Omagh bombing which killed 38 men, women and children and injured hundreds more. There was disgust and outrage from all quarters. The Real IRA essentially had cut its own throat - there was now real feeling that there had to be way of resolving the issues at stake, real motivation.
The Good Friday Agreement was borne, which allowed for power sharing and decentralisation of government. NI itself would take on some of the roles that had previously been restricted to London.
In a referendum, 89% of the population of NI voted for this agreement. I think people simply wanted to live in peace.
The road is long, and the power-sharing executive is at the moment dissolved because Sinn Fein (political wing of the IRA) had spies within Stormant (where the NI Assembly is based) spying on the Unionists. I'm sure this will be resolved. It's what the people want.
I'm no expert, but this is my understanding of the situation in brief.
