You may not have noticed, but if you’re a man in your mid 20s, your world has probably started to shrink. Friends you used to see regularly are dropping off into the periphery as they settle down, move away, or just stop being around. At the same time things like work and relationships are demanding more of your time and energy. Chances are, what you really feel like at the end of the day is some well-earned time in front of Netflix, taking you out of contact with people you used to see all the time. So the maths is simple: you’re losing old friends, and not making enough new ones to keep up.