The typical co-habitating couple in France sees the man as the older of the two, with an average 2.5 years of age difference between them.
In fact, 56 percent of couples see the man older than the woman, while three in ten couples are born within a year of each other
However, the statistics are changing when it comes to a woman having a younger "monsieur" according to a new study by France's official statistics bureau Insee.
It found that 16 percent of relationships had an older woman, compared to just 10 percent back in 1960, with an average age difference of four years.
The older female partner is perhaps most famously on show in France at the moment through the lives of Emmanuel Macron, the former economy minister thought to be eyeing up a presidency bid, and his wife Brigitte Trogneux, who is his former high school teacher and 20 years his senior.
Some 2.3 percent of relationships in France saw the man 15 years older or more, while just 0.3 percent saw a woman being 15 years older (or more). In other words, Macron is in extremely rare company.
A 33-year-old entrepreneur called Julien, who is in a relationship with a 46-year-old woman in Paris, told Le Parisien newspaper that the times are changing.
"Before, you could never even think of women going out with guys who were so much younger," he said.
"But today they do what they want with their lives and it allows them to have so many more dating opportunities."
The study found that the "younger man" phenomenon is more likely to occur among men who haven't graduated from university.
Lastly, the study noted that the older the woman, the more likely she will have a younger man. For example, only one in ten women aged 32 lived with a younger man, while one in two aged 92 could class themselves as "cougars".