In Medieval Europe marrying in your 20s was a lot more common, marrying very young was more of a thing the Nobles, rich & famous did.
And even then they often waited for the marriage to be consummated, they knew young mothers make births even riskier, something to be avoided.
Average life expectancy was low in Medieval Europe, average being the key word.
But this is of course a skewed perspective because the number was low due to high child mortality.
Those who survived childhood/birth had a decent chance of living into their 60s.