The phenomenon of romantic or passionate friendship among female adolescents is well-documented. It has been described as an “unusually intense friendship … that appears as emotionally intense as [a] romantic relationship but lack[s] explicit sexual interest, sexual activity, or both.” Across cultures, adolescent females in such relationships exhibit emotional behaviors “characteristic of romantic relationships, such as preoccupation, jealousy, inseparability, cuddling and hand holding.” In her mid-teens, Mary Wollstonecraft exhibited some of these characteristics. In 1773/74 she wrote a letter to her then best female friend Jane Arden. “I have formed romantic notions of friendship,” she declared. “I am a little singular in my thoughts of love and friendship; I must have the first place or none.” When she was twenty-one, she told Jane Arden that what she desired most was to live with Fanny Blood, who succeeded Jane in her affections. “To live with this friend is the height of my ambitions,” she stated unequivocally in a letter dating from early 1780.

On the surface, Marianne Woods and Jane Pirie looked like a textbook example of romantic friends. Female friends frequently used very romantic language in which to couch their feelings, and Jane's “dearest earthly friend” single-sentence note to Marianne has this characteristic. That Marianne asked Jane to destroy her letters suggests that Marianne's letters also brimmed with passionate intensity. The two engaged in public displays of affection, kissing, caressing, and fondling each other in front of the students. They visited each other at night and, at least on one occasion, shared a bed. Pirie, like Wollstonecraft, was jealous and obsessive and wanted to live with her beloved friend.

However, Marianne Woods and Jane Pirie became friends after adolescence. Between 1802, when they met, and 1810, when Pirie joined the school, life kept them physically apart. Though their romantic friendship, nurtured by epistolary exchange, deepened, they hardly knew each other. By the time they got together, they thought they did, but in reality what they knew was the self each had developed for the other in the letters. Neither had an idea how the other would react to real circumstances.