Friendships are like plants on a windowsill. The chemistry got them started. The watering keeps them alive.

Something has to keep a friendship alive after the part that made it easy. Instant chemistry explains why you started talking, but it does nothing about month eight, when your schedules split and neither of you is in the same building. Maintenance is the unglamorous half and the half that decides everything. Plenty of promising friendships end with nobody at fault except the calendar.

Message first this week without waiting for a reason. Put one recurring thing in the calendar so it stops depending on who remembers. Small regular attention beats a big reunion every two years.