Wait for Marcy by Rosamond du Jardin (1950)

Devon had a way of looking up into a boy's face that seemed to do something catastrophic to his will power. When Devon gave Steve that look of hers, Marcy felt younger than she had in a long time. "You kept looking at Devon," Liz teased her later. "What are you trying to do, absorb her technique?" "I should say not!" Marcy replied perhaps too sharply. And all evening she felt a sinking sensation within her. (from the back cover)