This One Summer by Mariko Tamaki

Every summer, Rose goes with her mom and dad to a lake house in Awago Beach. It’s their getaway, their refuge. Rosie’s friend Windy is always there, too, like the little sister she never had. But this summer is different. Rose’s mom and dad won’t stop fighting, and when Rose and Windy seek a distraction from the drama, they find themselves with a whole new set of problems. It’s a summer of secrets and sorrow and growing up, and it’s a good thing Rose and Windy have each other.