Definition of "fastidiousness"

I told him of the night I had seen her standing with bare feet in the garden, on the frosted lawn.Yes, he said, that was the sort of thing she did. But she had a fastidiousness, a certain personal reticence, that he respected. He never intruded upon it.

1952, Daphne Du Maurier, “Monte Verità”, in The Apple Tree

A sense of fastidiousness made the doctor choose the left side, near the door, when he slept in it himself with Clara.

1974, Graham Greene, The Honorary Consul, New York: Pocket Books, page 30