It's now an "out there" issue. Even for Ireland; it's now about the issues caused for us, not about the teamwork it was.
The UK is now a third country, psychologically, even if not yet legally.
That has real, important consequences.
If you have put yourself in that slot, you will not get a favour from an EU27 that regards you as such.
The open exasperation with idiocy like the Kipper Lie shows that is how the UK is now regarded.
Not, on balance, terribly wise.