Some years ago I read "Men are from Mars, Women are from Venus" out of curiosity because it was the original book that was supposed to help men and women in relationships understand each other better.

You know what my main takeaway from that book was?

That women are never fucking happy.

The author had only one piece of advice for helping women understand men in the entire book. That advice was that when there's an issue in the relationship, to give the man some time to digest everything before you sit down to talk it out. Dont rush him to talk before he's ready. That's it. That was the only advice for women.

The rest of the book was not even really advice for men to understand women, it was a laundry list of things men need to do to make their woman happy.

Now, it's been years since I read it but the one example I do remember was reflective of how I said that my takeaway from the whole book is that women are never happy.

The author cited this real world example of a couple they counseled. He was comfortable with their combined income. She was unhappy with their money situation. Even though they made ends meet. So in order to make her happy, he got a job that paid a lot better, but required him to put in a lot more hours. Now she was unhappy that he had to spend so much time at work. Even though he was doing it because of her. Never fucking happy.

Point is, I don't care if there even was a control sample. The OP is an accurate observation from the experience I've had with those kinds of books.