when did sophie jealous of geoff's silence?

Geoff scarcely spoke voluntarily. It was a tedious task to make him speak. After three years of passing out from school, he was almost a grown up. Sophie was extremely jealous of him now because he mostly kept silent and to her, this silence signified that his mind is wandering in some distant places. She felt a fascination for these unknown areas but the realisation, that she could never gain access to those areas of his mind, made her jealous.