After Independence Indian stand was clear, Either you become part of indian Union, or we will make you. While Pakistan played different card. Pakistan was formed in name of ISLAM, so the binding force was religion. And many Pakistani member claim that nation concept is secondary in Islam. (Coz when Islam was formed Nation state concept was not there, nation state concept emerge during French revolution and English Magnacarta).
Pakistan allowed princely state/tribal belt keep there identity and help pakistan to grow. Things were fine for few decades. Then came Mr Bhutto, he wanted a strong Pakistan with power centered at Punjab . He abolished old pact and try to make a central power. Bengali ppl saw it as betrayal. they felt cheated, This is not the pakistan Mr Jinna told them..
Same goes to Balochistan, Baloch ppl opposed Punjabi hegemony. Poor Baloch, they had no support, they were mascaraed in thousand, Iran didn't helped them. Where as on eastern front, India suffered the pressure of million and million of refugees. India beg to the world to take care of refugees, USA closed her eye and ignored our pain (A poor nation India feeding million of refugee).
India Cut pakistani Supply line and MuktiWahini won the war. Pakistani should be grateful to us for saving there 90,000 Soldiers. J R Jacob mention "On one incident Muktiwahini wanted to kill the Pakistani Generals, I told them, if they will touch them Indian soldiers will kill MuktiWahini".