Mistik Lake by Martha Brooks

While Mystik Lake includes some tragedy, the loss of the narrator's mother, it's basically a really sweet book.  Odella is the oldest of three girls coping with the departure of their mother, and she struggles with feeling overly responsible for her sisters.  At the same time, she's growing apart from her family and falling in love, ultimately coming to understand her mother a bit more.  I wish I use this book because I think a lot of girls would really love it, but it contains a fair amount of sex that is a bit much for 7th and 8th grade.