The elites that create and influence social trends are bleating nonstop about how we are overpopulated. The social dynamic now is such that any age difference more than 5 years is getting more and more looked down upon. Do we really think this is an accident? Like you noted, such things have an effect of locking men out of being fathers at an artificially early age. Also worth nothing that men marrying women who are lower in social status (often times due to lower age) is the norm throughout history.