There is a phenomenon in France known as Mothers-in-Law of Boys. I know a number of women married to French men, both English and French, and the consensus of opinion is united: French mothers-in-law of boys are head-cases.
What it boils down to is that their little darling is the most wonderful son on earth and you have no right to take him away from his mother's bosom. Only his mother is fit to choose a successor to care for her precious one, and no one, naturally, is up to the task as she is, of course, perfect in every way and how could anyone follow such an act?
My own ex-ing MiL has a bad case of it, but not as bad as the MiL of a friend of mine who almost caused a severing of links with her son's family because she hated her daughter-in-law so much. It got to the point where my friend told her husband that his parents were not to set foot in their house ever again. This was after a dinner a couple of years ago, with some friends and the parents-in-law. The husband had been building a swimming pool and it was going slowly because he has an extremely time-consuming job. In the middle of dinner, the MiL announced that my friend was ruthlessly overworking her husband by making him work on the pool so she could laze around even more (she doesn't go to work any more). An embarrassed silence greeted this remark and my friend tried to say that no one was making anyone do anything but that her husband had chosen to do the work to save money otherwise there would be no pool. The MiL brought up a whole load of irrelevent grudges until my friend could stand it no longer and told them to leave and not come back. So they did.
My own tried to upstage me at our wedding having almost caused the wedding to be cancelled and tried to insinuate herself into our lives sycophantically. She enjoyed cosy chats in the kitchen trying to worm out of me information about our relationship or inform me how I should be behaving towards my husband, keeping house, or what I should be wearing, such as never wearing more than two colours at once. This was said at a time when natural brown leather belts were all the rage with white shorts/trousers and blue shirts, so I was committing the cardinal sin of wearing three colours despite the fact that I was actually dressed in the height of fashion. You will understand why weekends at their place often left me banging my head against the wall.
On one occasion I had a surreal conversation with her about foreheads. It went something like this (translated, natch):
Her, peering at my head: "You have a very low forehead, don't you?"
Her: "High foreheads are a sign of intelligence, you know."
Me, dryly: "Really?"
Her, preening: "I have a very high forehead."
Me, ironically: "Ah."
and this from a woman who could barely put a thought into words before her husband told her not to be so stupid and to shut up.
I just had to relate some of this in my book as it is too entertaining to keep to oneself.