Part of my family is Galician, I'm Portuguese myself. Still, instead of breaking Spain apart I would actually prefer to see the whole of Iberia working together as a union.
The main problem seems to be where the capital would be placed since only Castilians would want Madrid. I only wish that we could agree on a small but memorable place like Santiago de Compostela as centre for that union.
Fragmented even more, our Iberia has little voting power in regards to negotiating with France and Germany in the European Union. If Catalunya has to separate, so let it be. In the end of the day we are all together on the same boat, can only wish that we could row together too.
This was the reason why Portugal split from a joint Spanish kingdom centuries ago.
Then we should see the foreign interests. France and UK profit from fragmentation in Iberia. Smaller countries are easier to place against each other instead of being an economical threat to them. Portugal remains a strong UK ally over the centuries while Spain sides with France, and now further fragmented as Madrid doesn't open the hand to a decentralized model.
Really sad. People in Iberia consider themselves more or less as part of the same family (which is true to large extent). We should be working together.