"We must catch up soon!" It's a phrase near universal in adult friendships - a text we've likely both sent and received. We mean it in the moment, with the best of intentions. But between work, family and endless to-do lists, a simple catch-up can become a logistical nightmare. Yes, we must. But we rarely do. It explains why research finds we lose around half of our friends every seven years. It's not that we're suddenly "fundamentally incompatible", says psychologist Dr Marisa Franco, but