The below answer is absolutely correct just let me summarise it to you in short
Okay partition of Bengal was needed because bengal at that time was a huge province and it was difficult to administer it and former viceroy and governor general though have suggested for it. BUT,
The British rather than to divide it to ease administration process have divided on basis of communities
(1) After Bengal partition, Bengolis became minority in their own state
(2) It was completely to break Indian Freedom struggle movement because Kolkata played a major role in pollitics
So, seeing it correctly and being insecure that they would not have authority of their own state as they would be minority they may have opposed it
and also there was a need of movement and partition gave a reason for the movement