I remember reading this YA book, which I believe had a sequel, in the mid 1970s. It took place in the early 20th century in the New York area, somewhere slightly north of New York City, possibly Westchester or Tarrytown.
The book(s) tell the story of the budding romance between the female protagonist and a boy who is a fellow student. At one point, the pair is cast to play Romeo & Juliet in a school production. Another slightly older female character (either a friend, or a sister), has a crisis (an unexpected pregnancy?) and she drinks a bottle of laudanum in response.
