How we cite our quotes: (Chapter.Paragraph)
Quote #7
I was jealous, wasn't I? I wanted to be Eldric's only friend. But that's not the way the world works, Briony. You have only one friend, but regular people have dozens.
Yes, I was jealous. I was practicing one of the seven deadly sins (although it doesn't actually take much practice). (16.94-95)
Briony admits her jealousy to herself, but frames it as a friendship-type jealousy. We're not convinced that's all that's at play here, but props to Briony for admitting at least part of the truth. When she says jealousy doesn't take much practice, she is admitting that she has felt this emotion easily and often.
Quote #8
I'd had visions of Eldric and Leanne on the hayride. Drinking from the same thermos; sharing a blanket; and when their fellow hay-riders left, lingering, perhaps, in the hay— (20.69)
The jealousy that Briony feels causes her thoughts to create and replay a painful vision of reality for her. By thinking of these things in detail, Briony's jealousy is essentially punishing her with heartbreak.
Quote #9
Cecil's lips were wet. "By God, you'll kiss me too!" Kiss me too! Fear whispered at the margins of my thoughts. (21.21)
Cecil has been jealous of Eldric since he first saw Briony and Eldric in the same room together—and he has never tried to conceal or control his jealousy, and this night is no different. What is different, however, is that he combines his jealousy with lust to make a very dangerous situation for Briony.