If India lets Kashmir break away from itself, then other states will follow suit. India is still not a coherent country, it has a long way to go and setting a precedent like this will be detrimental to India's future.
And remaining under Indian occupation has historically been, and will continue to be detrimental to Kashmir's future. We refuse to be held hostage to maintain the territorial integrity of a nation that entered our land as an occupying force, and has consistently denied us our most basic democratic rights for over 60 years.