Had Aglaya 'stayed a few moments longer', the prince would not have acted differently, but Aglaya might have understood his compassionate dilemma.
Whether or not Aglaya was proud, she totally misconstrued the way in which ‘his heart could feel love for another woman’. The prince agreed to marriage with Nastasya Filippovna through compassion for two lost souls - for 'the mad woman' and murderous Rogozhin - even though he truly dreaded both of them. His motive was to save Nastasya Filippovna from despair and Rogozhin from anarchy. He was certainly not head over heals in love, with anyone, since the time he first saw her heart-rending picture on the train.
I am less clear on the character of Aglaya, but here also, the prince was driven by compassion in action: by works of love.

