The Truth About Forever, by Sarah Dessen, is a masterpiece and worth every second of your life. The only times I would advice one to put this book down is if a) the house is burning down b) you've set something on fire, or c) you're invaded by a herd of Dinosaurs.
Macy Queen, the main character, is spending her summer looking after her genius-boy boyfriend, Jason's job while he's off at Brain Camp. She's bored (not to mention very unhappy) out of her mind sitting at the Help Desk, watching her mother prepare for various cocktail parties to boost sells on her new town house ideas, and silently grieving over her dad's recent death.
But things start changing when Macy joins the Wish Catering Crew, where she meets Delia, Kristy, Bert, Monica, and finally, Wes. Each and every one of her new friends help to show Macy--even if they don't know it--that she IS allowed to give in to her emotions, and that there are no rules to forever, as long as you make it the way you want it to be.