There is perhaps a survivorship bias in those studies, since divorce is so easy now, only people who are happy in marriage remain. i.e. reported happiness in marriage increases while everyone unhappy simply divorces and so the numbers would get swayed that way. Divorce rates have rocketed and women are very likely to leave marriages these days in many countries. So you end up with a tiny happy cohort that has no bearing on the wider population. So you should produce your sources to see how this is accounted for, ideally.

The problem with this is that women are of course happy when they have children, they love their children after all (father do too of course). But you don't love potential future unborn children do you?

Before having children they are a burden and a detriment to your lifestyle. After having them they are the best thing that could have happened to you.

And happiness is higher in countries with high divorce rates. Figures.

This could just as easily mean that people who are happy have more kids, not that having kids makes you happy.

This is like saying

"it could just be that people who are successful happen to be hard-working, not that working hard increases your chances of success"

The societal level of denial has reached new heights indeed.

Except you haven't actually given any evidence that kids cause happiness, just a correlation.

On the last point, i am not even sure there is correlation let alone causation. Successful people i know hardly work a lot (or they do but in short extreme stunts, like 3 weeks of 80-100 hours a week and then almost idle at 0-10 hours a week for the next 6 months). They mostly just tuned themselves into ability to get "into right place at the right time" at a rate way more frequent than regular folks, by having and consciously developing right personality traits.

> by having and consciously developing right personality traits.

Which takes a lot of effort and hard work.

> They mostly just tuned themselves into ability to get "into right place at the right time"

Which takes a lot of hard work

> then almost idle at 0-10 hours a week for the next 6 months

You have been tricked into thinking so, they just work so much more efficiently at some point and delegate a lot - at which point they are already successful due to their previous hard work