Distance changes which parts of a relationship can happen casually.

What distance takes first is not affection but the incidental. The unplanned bump into each other, the thing you would have mentioned in passing, the twenty minutes that happened because you were both there anyway. Once everything has to be arranged, the arranging filters out whatever is too small to justify a call, and the small things were most of the substance.

Send the trivial deliberately, since it will not arrive on its own. The unimportant photo, the two-line message about nothing, the voice note from a bus. Regular nonsense keeps a friendship in the present tense better than an occasional serious catch-up does.