I finished reading "Men Without Women" by Haruki Murakami. It's a collection of short stories. I loved the whole book, especially this quote given as advice to a man who lost his wife, who was cheating on him, and regretted that he did not understand her fully in life.

But the proposition that we can look into another person’s heart with perfect clarity strikes me as a fool’s game. I don’t care how well we think we should understand them, or how much we love them. All it can do is cause us pain. Examining your own heart, however, is another matter. I think it’s possible to see what’s in there if you work hard enough at it. So in the end maybe that’s the challenge: to look inside your own heart as perceptively and seriously as you can, and to make peace with what you find there. If we hope to truly see another person, we have to start by looking within ourselves.