There are a lot of unspoken rules about what friendships are supposed to look like. You don’t spend all your time with your friends. You’re not supposed to be obsessed with them. And you’re certainly not supposed to make an explicit commitment to spend your life with your friend. All of that is restricted to romantic partnerships. We talk to the author of a book who wanted to know why our culture discourages us from putting friendships at the center of our lives.