When another person is so important to you, and you're so used to periodically sharing your life experiences with them, you feel a strange ache inside if you've gone too long without talking to them. For whatever reasons, sometimes you might try to fight the urge to talk to them until you just can't stand it long enough. Perhaps you don't want to feel as though you're clinging onto their friendship too much.
I had a friend when I was 20 who was that important to me. About once every day or two we'd talk (Unix command) about random things in our lives on a special server at our university that was set aside for general, non-academic computing. A day or two would go by and everthing would be fine, but then at midnight some night I'd know I had to go to sleep in order to function properly the next day. And I'd be tired. Yet as I'd lay in my bed, I'd toss and turn and be unable to fight off the urge to logon and look for my friend. Almost every time that happened, I would finally give in to the urge at some random hour between midnight and 3 am only to find them logging into the server at the exact same time, feeling the exact same way.
I thought maybe we had a psychic bond. Or perhaps we were just in sync with each other enough that our minds independently chose to measure out equal time between our conversations. Whatever the reason, I have since hoped I'd one day be just as in sync with another person. Perhaps this time with the right person. A person who might love me as more than just a friend.