The goodbye becomes harder when nobody can honestly name the next arrival.

Partings are easier when there is a date. A goodbye with a next visit attached is a pause, while the same goodbye with no answer to when becomes something much larger, because the mind fills an open ending with its own worst version. What makes it heavy is often the uncertainty rather than the distance. Not knowing carries its own weight.

Where you can, put something in the calendar before leaving, however provisional. Where you cannot, say that plainly and kindly rather than promising soon. An honest unknown is easier to carry than a reassurance you both doubt.