Please help :( not even ai can find my book

[Reader]

I’m looking for a book I read over 5 years ago in a uk school library. It was a young adult book set in a nazi occupied country during world war 2. They show their distaste for the Germans by showing disgust to the local girls who date and parade around with the nazi soldiers. The protagonists were two childhood friends, a girl and boy who ran to join a resistance group, they picked out code names, the boys was ‘poet’ for his love of reading/writing. They carried out missions with the rest of the group, derailing supply trains was the most significant I can remember, one where they blew up a train station and another where the train derailed out on the tracks right next to the girl. The girl became infamous for her rebellious efforts, she falls in love with the boy but they get separated for the rest of the book. She continues her mission and succeeds and hopes he is waiting for her but there’s a time skip at the end of the book- the war is now over but it reveals he died as the girl is stood at his grave during this monologue, because they were separated we have no idea what happened to him. I loved this book, it was so powerful but I can’t find it anywhere, I must not remember enough identifying details of the plot because no book finder can find it :(

[HR-ML]

Hi Reader---

Sorry, I seldom read a young adult book. I'm old & partly gray-
haired. I recently had lunch w/ my friend, 6 years my junior,
and she had gray and lavender hair. She looked fab!

[HR-ML]

Reader---

If you use Amazon to acquire books or have a Kindle, you might have a record of you ordering this book on your computer?