I just lost a friend. I don’t know why. When I went to her the other day, after over a month of sudden and unexplained silence, to ask her what had gone wrong, she told me that nothing was wrong: things were exactly as they should be, with me out of her life. When I asked what I’d done, she wouldn’t say. She didn’t want to explain herself, she said. She said: “I’ve got a tendency to talk too much, so I won’t say anything.” It’s always been a troubled relationship. My friend—D—is funny, compassionate, generous to a fault. She’s a prolific writer, an inspiring teacher, and one of the most blindingly intelligent people I’ve ever known. But she is also one of the most difficult people I’ve ever known. She’s exhaustingly intense, easy to anger, quick to take offense, a holder of unyielding grudges. She’s incapable of apologizing or…