How we cite our quotes: (Chapter.Paragraph)
Quote #4
Perhaps [Abby] was in love with Carol, too. It put Therese on guard with her. It created a tacit rivalry that gave her a curious exhilaration, a sense of certain superiority over Abby—emotions that Therese had never known before, never dared to dream of, emotions consequently revolutionary in themselves. (10.24)
The jealousy drives a competition between Therese and Abby, in a friendly way, and it also encourages Therese. If Carol can be close with Abby, it gives Therese hope that she can grow close to Carol, too.
Quote #5
"I think I understand better now."
"Understand what?"
"Just—that you win."
"Win what?"
"What," Abby echoed with her head up, looking up at the corner of a building, at the sky, and Therese suddenly felt furiously impatient. (10.95-10.99)
Therese stops being jealous of Abby, both because Abby says she "won," and because she realizes how insecure and immature Abby is. Therese has no reason to be jealous of her because she is no kind of competition.
Quote #6
"I don't think Abby likes me," Therese remarked. "I don't think she wants me to see you." (11.11)
This is partly true, but Therese, who's young, doesn't yet understand Abby's complicated emotions. As Carol's friend, she wants her to be happy—but Abby also wishes that she could be with Carol, so she's torn about Therese.