The political union of England and Scotland was achieved without bloodshed and largely because folks in Scotland wanted a financial bailout to cover the utterly disastrous Scottish colonial efforts in Darien.
Personally I expect NI to peacefully unify with the Republic of Ireland at some point in the next 20 years? Or maybe not - all depends on how people vote rather than fighting?
I feel like you might not know much about the peace process in NI. If you’d like to see a return to things getting blown up and catholics being gunned down by loyalists, then suggest conducting a vote on joining Ireland and leaving the UK.