When a friend moves away, the miles prove how much they mattered. Text them about something small this week.

Distance works as a measuring instrument. Somebody who was simply around every day never got counted, because you never had to choose them; the shape of the day chose for you. When the miles arrive you find out how much of your life they were actually holding, which is useful information turning up at an awkward time. The friendship did not shrink, only the convenience did.

Text the one who moved about something small rather than something momentous. A joke, a photo of a street they know, a question about their week. Steady small contact keeps a friendship alive far better than occasional long catch-ups.