"A young girl, a Chinese or Vietnamese girl, slight as a child in her pale-green uniform, but with painted lips and cheeks, was coming along the corridor, pushing a cart. On the cart were paper cups and plastic containers of orange and grape juice. 'Juice time,' the girl was calling, in her pleasant and indifferent singsong. 'Juice time. Orange. Grape. Juice.' She took no notice of David and Stella, but they let go of each other and resumed walking. David did feel a slight, very slight, discomfort at being seen by such a young and pretty girl in the embrace of Stella. It was not an important feeling--it simply brushed him and passed--but Stella, as he held the door open for her, said 'Never mind, David. I could be your sister. You could be comforting your sister. Older sister.'"--Alice Munro, "Lichen"
Ay. Poor Stella. David thinks he's too good for her, but she's obviously the one with the more evolved mind. She understands his thoughts, and she graciously accepts him for who he is -- the kind of man who would feel embarrassed of being associated with her simply because she is no longer young and pretty like the juice girl.