When I was little, my mom moved somewhere really, really, really far away.  The downside was that, well, she wasn't around.  The upside was that, thanks to the magic of time zones, I could pick up the phone at 4am when I was in the middle of some existential teenage or college crisis and talk to her (expensively).  She died in 1996, a few months before I graduated from college, and the hardest thing has been all those times I wish I could pick up the phone at 4am and talk to her.  We grieve and then we get on with living, but there's always a hole.

The magical, special thing, though, is that there are a million and one happy memories (and even a few sad ones that are still welcome) to fill the hole.