“Between sips of kale juice at the Soho Grand, a chic Manhattan hotel near her apartment, she is explaining to me why time has hardened our view of adultery. ‘It’s because fidelity is the last thing left that defines a marriage,’ she says. ‘You don’t need to wait to have sex, you don’t need kids. You…”Tagged: Infidelity, The Economist, Exclusivity, Marriage, Commitment