Primrose it is repetitive, but I think it evolves.
In the first year she's very much everyone is going to want to be my friend and I've got to pick the right one. She ends up with Mary-Lou. That may have been to spite Darrell (can't remember) but she's not the one Gwen would choose given the choice.
Then years 2 and 3, she's looking for a good friend, a friend who will still see how great she is and force the others because of that friendship to see that she's important.
There's a big deal in year 2 about her being the only one who doesn't agree to give Daphne a second chance. But actually the crime against Gwen was worse. The others didn't listen to all her stories etc or be with her. Gwen would have had at the back of her mind. "that time when she asked me to check matey wasn't coming up the stairs-was that really so she could pinch something" or "When she told me she'd forgotten her hankie, she was really getting someone's purse" etc.
Year 4 (I think that's Zerelda isn't it?) she is bowled over by the glamour of her. So it's more that she wants to be friends with the important one, rather than have the others see her as important.
Year 5 is where she realises that it isn't the others that are wrong, it's her. And she does make an effort but no one bothers to notice. She really just wants to be accepted then.
Year 6 is a bit of a continuation. She wants to be accepted and doesn't really know what she's doing wrong. When she's telling about the situation with her dad, it's a bit like people posting on AIBU because they want to be told that they're right. When people say YABU they give excuses why they're NU and finally flounce off. She wants people to agree with her.
I think if they'd given her a chance in year 4 she'd have become a somewhat unremarkable outlier to the group. She's have not expressed an opinion of her own in case the leaders disagreed, but she would have tried, with a little help, to fit in. And I think she might well have been very generous.
I think Gwen's a much deeper character than it mostly appears. And I suspect deeper than EB meant to write her!