Help me find this book.

I don’t remember too much but it was an academy based

It was kind of bully (ik very general) BUT the main thing was challenging people was very important in the school… like you could challenge people in different subjects.
The main part that i remember that’s making me want to find this book was a scene where all the guys challenged her to a battle at the same time, and she was just sad and tired …. and she knew a final challenge was going to brought up from one of the guys she was particularly close to i think so she just said something like “get on with it” I DONT remember it’s driving me crazy.

also the girl was obsessed with this guy who she thought was brother but then fell in love with him i think.