Have you heard of “half their age plus seven” test? This is the convention around the age gap between partners that is considered okay.
What evidence there is, therefore, vindicates the choices of OKCupid’s users: women should pick men who are as close as possible in age to them, while men should look for younger women. A true economist, however, would look for better evidence, perhaps by comparing the marital bliss of random couples with varying age differences. Unfortunately for them, but luckily for the rest of us, people make their own choices – and are free to ignore silly rules of thumb.