She was several years older than the beautiful girl she had grown up beside.

Age had not mattered; Eileen's beauty had not mattered.

Marian was good looking herself.
She always had known that Eileen had imposed upon her and was selfish with her, but Eileen's impositions were so skillfully maneuvered, her selfishness was so adorably taken for granted that Marian in retrospection felt that perhaps she was responsible for at least a small part of it.

She never had been able to see the inner workings of Eileen's heart.

She was not capable of understanding that when John Gilman was poor and struggling Eileen had ignored him.