Have to say I know where AB is coming from on this. Sort off.
I've never been in the position to make his decision but my parentage is also from Northern Ireland but i was born and raised in England and although I'm aware and proud of my roots I feel English, support England and if I ever had have been in his position would have done exactly the same however unlikely the chances of being good enough to play for England. To be blunt playing for Northern Ireland would have felt like cheating my way into the international game and an insult to the good folk of Northern Ireland. I look out for the NI scores, love to see them do well and have even been to see them on one occassion but pulling on any countries shirt has to be done for the right reasons.