Where you live influences who becomes easy to see.

Proximity does most of the work in friendship. The people who become close are usually the ones who are simply around, repeatedly, without anyone having to plan it. Move far enough away and even strong bonds start to need scheduling, which is a much weaker force than accident.

If someone matters to you and you no longer share ground, replace the accident with structure. A recurring call, a standing visit. It feels artificial at first and it is what keeps the friendship alive where geography used to do it for free.