Or it could be that after a couple generations of no fault divorce, a divorce rate of over 50% which has created a vast public/private divorce industry and a “family court” system that is very hostile to fathers, many men are saying no when it comes to playing this game. The risk/reward math no longer pencils out.
If the drop in birthrate were limited to societies in which those circumstances prevailed, then the, shall we say, “male crisis” might be considered causative. However, below-replacement birthrates are found in countries with a wide variety of legal and social systems.