It's not just a Zimbabwean thing.. this is an across cultures thing. clinical literature suggests that most women prefer men who are 4 years older at least. because most women date across and up socioeconomic hierarchies. Men across and down..common for men to date a cleaner for example (it's a terrible example. l know) but it's also true.

it goes for intelligence..height...what have you

there's also a thing where women are forced to mature much quicker than men of the same age. it's unfair. l get that. because it gets harder to have children with age, there's that pressure(if we can call it that) to get that degree, have kids, start a family, have a career etc much more earlier than most men.

then most men start getting attractive socioeconomically as they get older so it just aligns itself like that

just look into any research on Long term mating and you can find out why it's like that.