If everyone could read just one book in the world it would be "If only he had been with me" by Laura Nowlin. This book is utterly heart-breaking but so fulfilling all at the same time.
The book teaches you to cherish every moment you have with someone because you don't know when it'll be your last with them. It also teaches you that you have to take risks with people you love specifically in a romantic situation. Autumn always loved Finny and Finny always loved Autumn but neither one of them wanted to make the first move after New Year's when they were in middle school. They both thought they would have forever, but forever was cut short when Finny died in a car accident with what would've been his ex-girlfriend.
Growing up next door to Finny, Autumn and him were instantly best friends because their mothers were best friends. Autumn gets a boyfriend and Finny gets a girlfriend but the romantic feelings between each other never died out, but only they got stronger. This book has personally taught me my guy best friend has made a lasting impact on my life and I wouldn't know what to do if he tragically died in a situation like this. "If only he had been with me" really made me stop and think about how I spend time with my friends and more specifically him, as we grew up only a neighborhood away and we as humans never know when it'll be our last time seeing someone. I believe everyone should read this book once and really allow it to sink in and realize how you need to cherish the people you have in your life as we're only here for so long.