But at least half the electorate doesn't actually support independence. You can't drag people out of a country against their will and it's retarded to think will not get uglier if Rajoy let's Catalonia go (not that he really can).
Look, whether Catalonia leaves Spain or not is not really my business or my concern. But looking at it objectively, the only way for Catalonia to be internationally recogized (and create a relationship with the EU, which is obviously needs to do) is if it leaves with the full agreement of Spain. I'm sure we agree on this, regardless of whether Spain does this willingly or due to foreign pressure.
To do this, Spain needs to alter its constitution: "The Constitution is based on the indissoluble unity of the Spanish Nation, the common and indivisible homeland of all Spaniards". They need to change that. Even if they add an amendment, it's likely the Spanish Supreme Court will rule that any amendment allowing seperation from Spain is in conflict with the above section. And that title falls under the protected provision, requiring a 2/3 majority in both houses, a general election, again a 2/3 majority in both houses and then a referendum in all of Spain. In other words: Impossible.