I have a whole database of aro & ace books as well as a bunch of starter posts here!
I'm a firm believer in the fact that the best representation is a book that is your taste in every other way, and also happens to have an aroace character. So here's a handful, but maybe have a browse of things that seem interesting to you/her also (tho, def books of varying quality in there, haha)
I'm leaning more toward traditionally published books here, as well as modern/contemporary settings that do focus on it a bit more clearly, rather than being incidental or implied. This does mean these lean younger, which I realise may not lean toward parents' taste...
Some good middle grades about tweens figuring out they're aspec: Olivia Gray Will Not Fade Away, Just Lizzie, Every Bird A Prince, Rick
Being Aro & Being Ace anthologies have a bunch of good YA short stories about..being aro & ace. obviously not all aroace.
Dear Wendy is a YA contemporary about two aroace students becoming friends
Funeral Girl is a YA paranormal about an ace (probably aroace) girl
Elatsoe is a YA contemporary fantasy mystery about an aroace girl (not so focused on aroace identity, but good)
Loveless is one of the most known - and it is one of the only traditionally published, popular books that's about and centred on figuring out and coming out as aroace, this is what most people will probably rec if you ask this anywhere else lmao
Is Love The Answer? is a manga about a student discovering she's aroace, with multiple aspec side characters too.
Sailing by Orion's Star (trilogy) is historical fiction about pirates with multiple aroace (man) MCs
Kaikeyi by Vaishvani Patel is historical fantasy with an aroace MC (though does marry and have children because she's royalty)
The Murderbot Diaries is a scifi series with an aroace agender MC - notably aroace because of nonhumanity, so not what everyone's looking for as a starter, but very relatable to many
Until The Last Petal Falls - an aroace QPR beauty & the beast retelling
If you're into indie urban fantasy I'd also check out Baker Thief/Painted Flock, and The Thread That Binds/The Tale That Twines
Beautyland is about an aroace woman who believes she's an alien because of how different she is from everyone else
and Convenience Store Woman similarly has a very aroace coded MC. These last two are less directly Explaining Being Aroace And Identifying As Such but very much show how it is being aroace (and neurodivergent) in an amatonormative world
Also, it's not a book, but I'd highly recommend checking out Koisenu Futari, a jdrama about two aroaces meeting and living together. It is very much about being aroace, and I think would be a good explainer for someone (if a little cheesy and straightforward in some ways, but I love it <3)
Konya Sukiyaki Dayo is another jdrama with an aromantic (probably aroace) MC that I also enjoyed recently.
I don't know if any of this is what you're looking for, but maybe it can be a start!