Nations are not naturally-occurring phenomena: they're socially constructed, actively produced and reproduced by communities of people. Northern Ireland is no different from anywhere else in that respect. To try to say that it is, in some way, an artificial entity is to base your conclusion on a false premise.
The thing about the border being "drawn by the British government to create a false majority" is problematic too for at least two reasons. Firstly, there's either a majority of people who want to maintain the Union or there isn't. That majority, as I mentioned in my last post, stands at more than 70% and includes, incidentally, more than 50% of Northern Ireland's Catholic population. Secondly, you're ignoring political context. The partition of Ireland took place in recognition of the fact a significant minority of people, concentrated in the north of the island, didn't want Ireland to have Home Rule and had taken steps (the formation of a mass civilian army and the procurement of arms) to resist governance by a monotheistic Irish state. Had Ireland not been partitioned under the Government of Ireland Act 1920, the result would have been a protracted, bloody civil war that would almost certainly have culminated in, and been settled by, some form of partition anyway.