I quite agree.From time to time in life it is necessary to take a reality check. Eventually this conflict will lead to some sort of negotiation since it is clear that Russia has no realistic chance to both conquer and then control the whole of Ukraine. Before that negotiation gets underway, regardless of what happens elsewhere in their country, the Ukrainians' reality check will force them to accept that the Donbass and Crimea are now under permanent Russian control. That fight is simply no longer worth continuing however regrettable that may be. Once that conclusion is accepted it becomes much easier to talk of a Ukrainian state aligning with Ukrainian identity.
As to your rough comparison with the Irish situation one of the keys to the uneasy peace brought about by the GFA was the Republic of Ireland giving up its claim over Northern Ireland in return for participation in all sorts of cross-border bodies. So Ireland can concentrate on the needs of people south of the border and the northern Loyalists can live with much less paranoia about Republicanism.
Long-term peace has to involve a degree of compromise according to the reality on the ground. Ultimately Putin claims he wants to re-unify the Russian peoples while Ukrainians, en mass, reject the idea that they are in fact one of those peoples. Ceasing the conflict over who should control Donbass and Crimea will be an important part of re-establishing peace in the region.
As far as the long term peace goes, I'm hopeful that whatever (very heavy) arms have been distributed to the Ukrainians does not end up in the hands of various nasty militias that have existed there for some time.
We may be hopeful that Putin's successor is not so blindly revanchist. Putin will not be here in 5-10 years.