The second thing I used to do to maintain friendships was to contact my friends when my depressive episodes were over. Whether it was an email or a telephone call, I would say, "I'm back," and meet them for lunch or dinner (or talk on the telephone) to catch up on their lives. I made it a point to send birthday cards (even though it might be months later).
I let them know that even though I may have missed important events or milestones in their lives, it wasn't like I didn't care about them. And I focused on letting them talk.
I think that one of the worst aspects of this illness is that it causes people to become self-absorbed. At least, that's how I felt. Of course, when I've been really sick, all I could think about was how I was going to get better. And...the everyday matters of other people's life weren't very important to me.
But once I was well, I realized that it's not acknowledging the small stuff that hurts people's feelings and makes them feel like you don't care about them. After all, friendship is defined (at least by Wikipedia) as cooperative and supportive behavior between two people.
I'll end this post by sharing a few of my favorite quotes on friendship:
"What is a friend? A single soul dwelling in two bodies." ~Aristotle.
"Friendship is born at that moment when one person says to another: 'What! You, too? Thought I was the only one.'" ~C.S. Lewis
"The glory of friendship is not the outstretched hand, nor the kindly smile, nor the joy of companionship; it is the spiritual inspiration that comes to one when you discover that someone else believes in you and is willing to trust you with a friendship." ~Ralph Waldo Emerson