French gossip is very dull. The culture is such that nobody talks about the sex life of anyone; there is no "That woman at number 46 is no better than she should be" or anything like that. The conventional view is that a man who is cuckolded is a figure of fun, not sympathy, and a woman whose husband strays has only herself to blame; it's not his fault. And nobody wonders at the President straying, if that emerges. They think that any powerful and successful man is bound to attract women. If he is tempted to respond, well the law of averages suggests that he will. After all, the woman is one of hundreds or thousands, so the percentage is very low.
The privacy law is toothless, but symbolic. A paper which, or a person who, contravenes it only gets fined a small amount. The thinking is that the ignominy is such that the penalty need only be tiny.