Need recommendations for a book for my Girlfriend.

My GF basically never reads and has had a hard time finishing novels. However I am a pretty avid reader and have been trying to get her to read more. Recently she has been showing some interest in reading and wants me to recommend her a longer book that she’ll actually want to finish. I have a feeling our tastes in literature are (will?) probably be pretty different. I’m very much a depressing or cynical classics fan and I think if I recommend her something from my wheelhouse it’ll forever turn her off from reading.

So I guess what I’m asking for is some light hearted but still mentally stimulating longer books that will foster a desire to want to read more.

Shes such a bright person and I’d love if we could connect over reading.

Thank you so much in advance for all recommendations!