"Melanie was fifteen years old, beautiful, and had never even been out with a boy, when, for example, Juliet had been married and dead at love at fourteen. She felt that she was growing old."
Being influenced by fairy tales and other types of books about love, Melanie is growing her own idea about it. The boy she would ideally want for herself is something close to a Prince Charming, which is the complete opposite to Finn. It could be seen that this line has an ironic undertone, because a fifteen-year-old child, influenced by romantic novels about love, is seeing herself as growing old for it.
"The garden turned against Melanie when she became afraid of it."
This line is a perfect example of things being what we perceive them to be. Melanie came out as a fairy tale bride into the night and the surrounding nature enhanced the feeling of this magic. But, as soon as Melanie, in her own mind, starts seeing the threat in the night and the thick garden, she perceives it as evil and trying to grab her.
"Since she was thirteen, when her periods began, she had felt she was pregnant with herself, bearing the slowly ripening embryo of Melanie-grown-up inside herself for a gestation time the length of which she was not precisely aware."
The link between physical and psychological female maturity is what is being described here and the metaphorical connection between the beginning of emotional maturity, of finding oneself and pregnancy, another aspect that comes with female physical maturity, further emphasizes this connection.