There is a specific kind of blindness that infects a marriage when you trust someone completely. You stop looking for the cracks in the foundation because you assume the house is solid. For ten years, David and I had a beautiful, boring, perfectly solid marriage.

Or so I thought.

Three years ago, David started developing a strange, unbreakable routine. Every single Friday, right after he finished his shift as a structural engineer, he would drive across town to my older sister Karen’s house. When I first asked him about it, he brushed it off casually.