Flaming Youth.

When Mona Frentiss dies, she has her confidante "Doctor Bobs" watch over her family, especially her youngest daughter Patricia. The family has been raised in a most unconventional manner, with Mona having a much younger lover and the father Ralph keeping his own lover on the side. As Patricia grows older, she attracts the attention of her mother's former lover, the much older (than Patricia, who in the book is in her early to mid teens) Carey Scott. Patricia tempts fate with her wild ways, nearly loses her virtue to a musician aboard an ocean-going boat, and is saved in time by Carey. Realizing that he is the man for her, she settles down into an experimental marriage.