It's the terms on which we interact and the degree to which we do it that can lead to conflict.
The extreme alternative in terms of separation would be the idiotic, self-destructive post-imperial strutting that's accompanied the UK's drive for Brexit and an ill-conceived isolationism that embraces the fantasy of a country being granted everything it desires from some sense of misplaced entitlement while ceding little or no ground in return.
If Scotland wanted to behave "selfishly", as you frame it, then it would have kept a low profile during the current Catalonian unrest. Much has been made in the past of the likelihood of Rajoy opposing any idea of Scotland's accession to the EU if Brexit proceeds and another referendum leads to Scottish independence. He in fact chose to differentiate the Catalan and Scottish situations, but he doesn't seem like the sort of leader one wants to cross when he can wield a veto. So the selfish, conveniently diplomatic course would have been to cravenly remain silent.
As it happened, Sturgeon was one of the first leaders within a EU country to express public concern at the violence surrounding the Catalan referendum and the intransigence of the Rajoy regime, closely followed by Belgium, then some of the Nordic countries.
Note that neither she nor I have stated categorically that Catalonia should be independent. The principle of self-determination means precisely that. But if Rajoy is so certain of the majority Catalan opinion, then logic would dictate that he'd let a referendum proceed and not send in the stormtroopers against nonviolent crowds.
As it is, it looks like there'll be elections in Catalonia in a few months' time. Unless Rajoy chooses to incarcerate the entire leadership of all the opposition parties in that region or restrict voting rights or otherwise suppress turnout by whatever means, then maybe we'll have a clearer indication of public opinion.
= new reply since forum marked as read