The EU's priority is the EU. Provided the EU can contain any UK efforts to create damage, then that is pretty much the only real interest the EU has in the UK at this point. And as far as the EU is concerned it is an entirely domestic UK matter if the UK chooses to move towards reintegration with the EU; complete poodling to the US; or fission into smaller states. The key point is that the EU's priority is the EU, and that means containing any attempts by the UK to inflict damage on the EU. The EU is well aware that the Cons have a lock on the UK electoral system, and that the Cons are in hock to ultra-right and the ultra-rich, and so in effect the EU is well aware these are a problem: these are not partnership material. Partners are friends who can be trusted, and the UK no longer justifies that term. In many respects the EU now views the UK as a potential threat in almost every respect.
If individuals in the UK wish for the UK to Rejoin, then it is up to them change the facts within the UK, or to split up the UK into manageable chunks. Not to wail about the EU.
De facto the vast majority of the people of Northern Ireland are EU citizens, and as such the EU is doing its best to protect their rights under the WA, and the interests of Eire. Again, if the UK doesn't like that, then that is the UK's problem. The EU will - and is - protecting them, and itself against the very real threat that is attacking it. The effect on the wider UK is not a real concern to the EU any more.