The man who wrote the diary displays a very strange reaction to what (for me) appears to be a negligible accident - having his and his friend's (with whom he was kissing) glasses entangle and fall on the ground.
He picks them up, (some other woman comes in?), and he leaves in a hurry, despite him liking the woman he was together with at the moment, and her asking him to stay. He even goes as far as remarking that he felt as if he had stumbled upon a corpse in the darkness.
What was this scene about? Why did he leave her, and what did the glasses have to do with this? The whole story of the book hinges on this breakup, and yet the breakup isn't explained, even in the slightest detail.