Spousal rape still happens, most rape happens without consequence. It's that women have access to birth control that allows them to control how many kids they have.

The reason replacement level is down is because birth control (eg levongestrol) was invented and became in use in the 70s, with global advances in human rights and better financial equity in many places. Since then, the average person has gotten poorer and poorer, it's harder to afford a home, etc, because income inequality has increased and ownership has been stolen from us transaction by transaction.

Look again at my reasons listed for why women do and don't choose to have kids. One of them is financial reasons.