I pulled my hand away. “I know all of that,” I said. “I read a piece about it once in Cosmo. And you know what I was thinking when I was doing all this crazy stuff with colored stickers and ringing people up under false pretenses? What would make it easy would be to find just one deleted email, just one scrap of paper in a pocket, that would show Greg had been having an affair. Or even just one occasion when he wasn’t where he was meant to be, or a missing afternoon when nobody knew where he was. Forget denial. Then I could just get angry and be sad, and my life would continue. There’s no trick to proving somebody’s having an affair. You catch them at it, just once. But how do you prove somebody’s innocent? What do you suggest?”

Gwen shook her head. “I don’t know,” she said.

“You have to do something like this,” I said. “Something obsessive and excessive. You have to fill in all the gaps, then the gaps between the gaps so there’s just no space for this relationship. You know I went to see the police?”

“Ellie, you didn’t!”

“I told this woman officer I was convinced my husband wasn’t having an affair. She didn’t seem to believe me. I don’t think she thought it even mattered whether he was or not. The case was closed. This wasn’t something she wanted to hear about. But if I showed those charts to the police, do you think it would make a difference?”

Gwen frowned at the charts for a long time. “Honestly?” she said.

“Yes.”

“This is amazing,” she said. “Scary but amazing. I don’t think the police would pay much attention to it, but if they did, they might say, ‘Perhaps he was seeing the woman while he was doing other things. Perhaps she met him while he was buying his sandwich, perhaps she went with him in the car to his meetings. Or you might be right. Maybe they didn’t meet in that month. She could have been away and they were meeting up again on the day they crashed.’”

I took a deep breath. My first impulse was to be angry with Gwen, to shout at her and show her the door, but I stopped myself. She might have humored me. Instead she had said what she really thought.

“And if they said anything,” Gwen continued, “it would be that you’re ignoring the only piece of evidence that really matters, which is that Greg and the woman died together. What in the end can you really say to that?”

I thought for a moment. “That it’s difficult to be innocent,” I said. “And to prove you’re innocent is impossible.”

Chapter Eleven