When modelling commuting patterns in a borderless environment, it's the square of the distance that matters rather than the distance itself.
I'm not sure it would apply in aviation though. There are all sorts of other complications like alternative means of travel. Look at Dublin and Newcastle to London as an example. Both airports are a similar distance and have similar catchment, but because of the sea blocking rail and road as means of travel, passenger numbers to Dublin are 10 times higher.
Even on long distance, there are factors like historic cultural ties. E.g. look at routes from Europe to the West Indies where routes from the UK go to the former UK colonies, from France it's their former colonies and overseas departments, from The Netherlands it's Aruba, Bonaire, Curacao, Sint Maarten, while from Germany, which has no real ties, it's a mix and match of all of them.