Giovanni's Room Passivity Quotes

How we cite our quotes: Citations follow this format: (Part.Chapter.Paragraph)

Quote #10

I turned and held him in my arms staring above his head at the wall, at the man and woman on the wall who walked together among roses. He was sobbing, it would have been said, as though his heart would break. But I felt that it was my heart which was broken. Something had broken in me to make me so cold and so perfectly still and far away. (2.5.195)

What does David mean when he says that his heart is broken? How is this different than the way that the expression is commonly used? What keeps David from sympathizing with and reaching out to Giovanni?