There is a slight dilemma - maybe even melancholy - in knowing someone so well and failing to find a proper excuse, or common ground, to communicate. When the words are lost, or rendered meaningless or inconsequential, don't you mourn a little? Because not so long ago, you could almost talk - maybe even laugh - about anything at all. So what happens then? What gets in the way? Is it ego? Apathy? Laziness? All of the above? 
Been there, done that. But I also deliberately revisit my past, just in case I've overlooked someone or haven't given them ample chance. I revisit with both past and future in mind. And I watch if their present resonates with my now-self. Sometimes I'm happy to pick up where we left off. Sometimes I'm happy to pick up and go.