She did not tell him

And now here she was telling him it was over. “Why?” he asked. He taught ideas of nuance and complexity in his classes and yet he was asking for a single reason, the cause. But she had not had a bold epiphany and there was no cause; it was simply that layer after layer of discontent had settled in her, and formed a mass that now propelled her. She did not tell him this, because it would hurt him to know she had felt that way for a while, that her relationship with him was like being content in a house but always sitting by the window and looking out.