Let's Not Meet

Dramas and Films where a main part of the plot is the fact that the main characters do not meet for the majority of the story.  Mostly, this will be because they are communicating from different points in time, but there may be other reasons. They may meet in the end, or never meet at all. 

I am avoiding spoilers as best as I can.  I will not specify whether the characters eventually meet in the end or not. 

Unrelated backstory but the first time I encountered a trope like this was in the Tv show from over in the USA called "Z Nation" about a zombie apocalypse where for the first 3 seasons, one character communicated with the main characters through radios only, but at the end of season 3, he manages to meet the main group in person for the first time, and I loved that moment so much that I'm desperate to find dramas with a similar trope.