The emotional moment a man asks a woman to be with him for the rest of his life, why does he get down on one knee? By HAYLEY RICHARDSON

https://www.thesun.co.uk/living/1717093/this-is-why-men-get-down-on-one-knee-and-other-interesting-facts-which-explain-the-modern-marriage-proposal/

Postscript: I didn't read this though. But this is the question / answer I was looking for.