It makes sense that we should lose some friends over a lifetime. In fact, it’s necessary and it can be ultimately positive. We make friends so often, particularly growing up, for social survival and convenience more than anything else. At school, we grab whoever is closest, whoever most closely resembles ourselves, whoever was sat next to us alphabetically on the first day. We assess our worth in a complex system of gossip, vivacity and extroversion and gravitate towards the friendships we can make work. We make nemeses, too, and fight our way through the ferocious fragility of adolescence. Some people are lucky and make meaningful friends then – but a lot of us don’t and it makes sense that so many of our high school friends drop out of our lives. At least by university, we can make friendship choices using our fully developed frontal lobes and hopefully slightly less restless senses of self, but even then we are building our identities and our networks from youth, naivety and hope. The friends we make as adults – at work, by chance, through our children, online, at our boyfriend’s sister’s house party – have the greatest chance at longevity but even then, they disintegrate and they fail.