yuebaili, you're trying to distort the meaning of democracy by taking it to the extreme. If you, as a resident of Sweden, manage to convince your family members that the area around your house and your backyard should become an independent country, should Sweden agree to your demands on the basis of "democratic majority?"
If your kids demand that their room be declared an independent country and others should not step into it, would you agree to it?
If the residents of a small Swedish town were to ask for independence, would Swden give it to them?
The purpose of these examples is to demonstrate that when referring to "democratic majority", the context is usually a national majority, not a localized one. As long as the national majority in India remains opposed to Kashmiri plebiscite, there cannot be one just because the Kashmiris ask for it.
There are good reasons for the national majority in India to be anti-plebiscite. It has been the firm belief of Indians, just like Europeans, who were fighting each other for thousands of years, that unless they joined together, foreigners will continue to invade India and inflict atrocities upon it, like they have done for the past 1200 years. When the British came and ruled India for 150 years, it finally dawned on Indians that, "United we Stand, Divided we Fall". And hence, any separatist movement in India after independence has been crushed with brutal force, with the rest of the country supporting the measures taken.
India is just like the EU, except that it is a single country. What the EU is trying to do, India has already done 62 years ago. India's independence was achieved by integrating more than 500 independent states in 1947.
There obviously cannot be a reversal now just because one component of the federation has not learnt through its mistakes over millenia.