A useable human takes about a decade to produce, two decades to become fully functional, and three to become great. That's about an order of magnitude longer than any other species which makes us slow to evolve through darwinian selection. Which would of meant extinction by now but for our ability to transmit and evolve culture in between generations.

Biologically speaking the definition of female is the gender that put's more effort into offspring. With humans, though, it required a lot more specialisation that it usually does. Humans are hard to make and a well looked after one makes for a vastly better adult. If only in terms of physical size.

The result of this is that the human sexes are very specialised for their evolved role in reproduction. I think it's nearly impossible to have a happy relationship without understanding at least from a high level what exactly these specialisations are. It certainly helps.