Carol, who grew up in the 1930s, doesn't rebel against conformity the way Therese does. Perhaps this is the "courage" Carol sees in Therese and begins to draw from as the novel progresses and Carol rebels herself.

Here is another rude thing said to Therese, this time by Carol. Carol eventually listens to Therese in the end, but she acts like a stodgy old broad first before accepting that Therese, although young, still has knowledge.

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.