How do I start saying this.... the book is not good.
TL;DR: Lost plot elements, forced underaged romance.
Some plot elements introduced at the beginning of the story were pretty much dropped in the middle of the story, and half of the group disappeared, like I know I'm bad at remembering character names, but if you aren't giving a backstory to most of them then a rock would've been a better plot device.
The random shoehorned romance, if you're introducing a character as Frenchie's cousin, I don't think that it would be a great idea to start a romance between them. Even thought Rose wasn't his cousin, there could've been traits that helped make her seem like an actual person. Instead, she was only there for a forced romance. I wouldn't have minded the romance if she had a personality, like Katniss from the Hunger Games. Katniss has Peeta but she isn't 'tied' to him, because she does her own stuff and has a personality.
I would suggest you read another book than this one