It’s slightly more complex. The right to self determination is not automatic, there are many condition precedents to be fulfilled and it is cross linked with territorial integrity. It’s quite a mess in international law.
It’s not just the majority of an area voting.
http://www.e-ir.info/2014/05/02/does-self-determination-entail-an-automatic-right-to-secession/
The article makes mention of the Montevideo Convention, which is used as a guideline for the basic requirements of statehood and these same requirements were taken in to consideration when discussing the future of Yugoslavia and her successor states.
The basic requirements are (quoted from the article);
...a permanent population, defined territory, a government, and the capacity to enter into relations with other states.
A concentrated population is there. There is a defined territory and there is a semi-autonomous government in place that has political capacity, until now even recognised by Madrid. Catalonia is a de facto state, but there are political forces that will prevent this going any further and the article seems to corroborate what I have said.
It is evident that recognition (especially from powerful international community members), a clearly political act, has proved to be decisive in certain situations
It is evident that states practice reflected whether or not national interests were at stake, since those that opposed secession were often the same ones worried by secessionist movements at home (Spain and Cyprus, inter alia)
The EU, Russia and China will not recognise an independent Catalonia because doing so will validate secessionists in places like Chechnya, Flanders and Xinjiang. For Spain it would hit even harder as recognising Catalonia likely triggers the Basques.
The national integrity argument is also seemingly flawed as its only brought up when it suits the power players.
Russia, for example, has trapped itself in a self-spun web over this. Russia signed off on Abkhazian and South Ossetian independence because Georgia mobilised their military against them and the Russians claimed independence would guarantee their safety. However, Russia refused to recognise Kosovo because the Kosovars we no longer deemed to be under threat from Serbs, then the Russians went and fiddled in Ukraine and ''accepted'' Crimea's secession from Ukraine. Meanwhile, how many times has Russia gone to war with the Chechens (Safety argument)?
Its all politics. The EU will be the same. The power players don't want to stamp on one another's toes nor do they want to be the ones that are compromised by either losing territory or encouraging further secessionist movements at home or elsewhere.
There is a fragile balance between the principles of territorial integrity and self-determination, and careful considerations are needed before applying them to international affairs. Dismissing self-determination in too simplistic terms – as it was often done before Kosovo, to preserve territorial integrity – generated great and widespread unfairness.
In this case, ''territorial integrity'' is just bollox-speak for maintaining the status quo at the old boy's club.