The Handmaid's Tale: This should absolutely be mandatory reading in high school for everyone. Women's reproductive freedom has been a hot topic for decades, but this book takes the consequences of those freedoms being abridged to a horrifying extension. I don't think it's possible to read this, especially as a woman, and not be aware of how important it is to ensure that we have control over our own bodies.
The Stepford Wives: This is a quick and haunting read. When Walter and Joanna move to Stepford, it seems like it's full of perfect happy families. But there's something...off...about the wives. It's a scathing statement/satire about what men really want.
The Interestings: This novel explores long-lasting friendships, and the kind of competition that works its way into them. A group of young boys and girls at an artsy summer camp bond together and pledge to remain friends forever. It's not as easy as that, obviously, and the book explores how friendships, especially female friendships, grow and change over time and the damage that the self-induced pressure to be "special" can inflict on lives that turn out to be more or less ordinary.
Persuasion: Love and relationships are a huge part of life in general, but especially when you're young and just figuring out how to handle other people's hearts and how you'd like them to handle your own. Anne Elliot spurns the marriage proposal of Frederick Wentworth, even though she loves him, because her friends and family convince her he's not good enough. She's in her late twenties when they meet again and their fortunes have shifted...he's now a hot prospect and she's staring down spinsterhood (boy am I am so glad we don't live in Ye Olden Days anymore). She still loves him, but fully expects that she has lost him, and the heartache this causes her until (spoiler, but not really because this is Jane Austen) they get back together makes you really think about how you treat other people.
Anna Karenina: I know, this is a monster novel, clocking in at well over a thousand pages. And Russian literature, with its naming conventions alone, can be hard to get into. But this story, about a young mother who is married to a bureaucrat with whom she has a satisfactory relationship but does not love, and falls into a passionate affair with a young nobleman is AMAZING. Is Anna brave? Is she selfish? What's a better situation: a settled and content existence or a passionate and completely unstable love affair? There's the whole side plot about Kitty Shcherbatskaya that progresses independently and is also good in its own right, but it's more of a slow burn than Anna's story, which raises all kinds of interesting questions to think about.
The Awakening: This too is a book about a woman living a conventional family life with a husband she doesn't really love, who falls for another man and finds the prospect of a relationship with him infinitely more compelling than continuing her staid existence and a wife and mother. This explores similar themes to Anna Karenina, obviously, but it's not quite as good. It's also not nearly as long, though, so it might be a good starter before you tackle the beast.
The Girl With The Dragon Tattoo (series): As important about decisions about what love is and who to love are a central part of young womanhood, there's much MUCH more to your life than boys (or girls, or both). Lisbeth Salander kicks ass, takes names, looks how she wants to look, and has the sex life she wants to have. She has her own goals and pursues them and romantic relationships aren't something that's especially important to her. Being single or not making your love life a big serious deal is totally okay.
A Game of Thrones (series): The main female character in this series, Danaerys Targaryen, begins the books by being sold by her brother to a tribal warlord with whom she has no common language. But Dany and Khal Drogo's love story ends up being one of (if not the most) happiest relationships depicted in the series. When he dies, Dany turns her focus to learning how to rule a city. She has relationships, but they take lower priority than her personal goals. There's an interesting, complex model of any kind of woman you'd want to be over the course of these novels: Catelyn, Sansa, and Arya Stark, Brienne of Tarth, Cersei Lannister, Maergery Tyrell. You don't have to be just one thing. You're allowed to have internal contradictions.
White Oleander: I don't know any woman who has a perfectly pleasant and smooth relationship with her mother. I don't think those exist. We love them but they drive us crazy: I think both sides would agree with that statement. The fraught relationship between Ingrid and Astrid is an exaggerated one, as are Astrid's relationships with her foster mothers, but coming to terms with your mother for who she is and recognizing and reconciling the parts of you that are like her are important (albeit difficult) parts of growing up.
The Devil Wears Prada: It's a lightweight, kind of fluffy read, remarkable to most because of its thinly-veiled look at Vogue editrix Anna Wintour. But there's also an important lesson in here about work/life balance. It's tempting to, like Andy Sachs, let everything else in your life fall by the wayside when you first get into the workplace, and if you've got big goals and are willing to let your personal life go for a bit while you chase them, go for it! But we all learn eventually that we can't be both a perfect employee and a human with a functional social life, and learning where to draw those lines is an important lesson. Just because you've got the job a thousand girls would kill for doesn't mean it's the right one for you.