Have you talked to her about what the problem is? It doesn’t sound like you have. In which case, that almost certainly is at least part of the problem
Seriously: she is really good at evading conversations like that. I have done all I could imagine to get her to actually talk about kids and our non existing intimate relationship. She always either gets angry or silent or changes the topic. Without knowing anything about me, some people are always inclined to believe something is wrong with me, not her. That’s so utterly unfair. I always treated her like a princess, work out and try to be healthy and look good, share all chores and take care of the house. Really if something is wrong with me she has never told me. Like I said I have no idea what to do.
It's not like fertility rates just started dropping in the 1960s. TFR in the US 200 years ago was over 7. Wealth and fertility are anti-correlated almost universally, at least at the population level.
Why did people centuries or millennia ago have so many children? Partly economic reasons: they can work your farm, and they can support you when you're old. Partly because sex is great and children are a frequent result of it.
The economic reasons fade as wealth grows, and the connection between sex and having children gets decoupled by technology. That leaves innate desire, which just doesn't seem to be that strong. We don't need to posit some recent drop in innate desire to explain the drop in fertility rates. The historical behavior we see fits just fine with innate desire being constant, and just not that high.
It varies from person to person; some of that variation is social/cultural influences, some is life experiences/circumstances, some is just randomness-but very likely it has a genetic component.
If certain alleles predispose one to be more likely to desire to have children, then in a society with strong social pressure to have children and limited availability of contraception, the selective pressure in favour of those alleles is going to be limited; in a society where social pressure to have children is low and contraception is readily available, those alleles will significantly increase the odds of having children, likely resulting in their frequency increasing over time, and maybe even (in the very long-run) a rebound in TFR
There are a lot of variables that are hard to control for.
When talking about hormone disruption, I think people over-focus on how that affects the ability to have kids. But that overlooks how hormones can change behaviors and desires. I don’t see anyone rebutting the fact that testosterone levels in prime-age men have dropped by half compared to the 1960s. Yet nobody seems to be talking about that as a probable cause in the drop in fertility rates. Even if these men are technically able to have kids if they want. Is it possible that the drop in testosterone levels means that men are less interested in having kids, and perhaps less able to persuade women into doing so?