It's not the cheating. It's the hunger for an alternative. The refusal to accept unhappiness.
From a distance, it makes perfect sense that the people and the things you think will save you are the very ones that have the power to disappoint you most bitterly, but up close it can hit you as a bewildering surprise.
He made me think of all the books I hadn't read, and all the ones I'd read but hadn't fully understood.