It was the immemorial battle, brought by circumstances to a crisis, between the race and the individual, between tradition and adventure, between philosophy and experience, between age and youth.
Yes, it was "something different" that he craved.

He had known Margaret too long; there was no surprise for him in any gesture that she made, in any word that she uttered.

They had drunk too deeply of the same springs to offer each other the attraction of mystery, the charm of the unusual.

He was familiar with every opinion she had inherited and preserved, with every dress she had worn, with every book she had read.
As a whole she embodied his ideal of feminine perfection.

She was gentle, lovely and unselfish; she never asked unnecessary questions, never exacted more of one's time than one cared to give, never interfered with more important, if not more admirable, pursuits.