My grandfather married my grandmother in 1914, she was 15 and he was 17. My mother married my father when he was 18 and she was 16. I married my wife when I was 22 and she was 18 and it quite possibly would have been sooner had I not went to Vietnam.
Today people have the luxury of marrying at an older age. Also the luxury of good healthcare (well, that’ll end soon!) that has increased life expectancy. My husband’s grandmother was married at 15. Times were tough, children were plentiful, and parents needed to get them out of the house! Think of Tevye’s daughters in Fiddler on the Roof!