Yes, if we read history about the period just after partition, we found that the binding force of two nations theory started loosing its impact. people soon started showing their affiliation with their language and culture rather than just sticking to religious ideology.
The slogan of ‘Pakistan ka Matlab kia, La ilaha Illallah’ were replaced by new slogans of Division.
Exploitation by Government and Army did played its role, but our society as a whole forgot that centuries old traditions which remain intact even centuries after conversion to Islam, were as important to Bengalis and other communities, as religious ideology, while demanding a separate country.