The fairytale-like story of a prince/nobleman falling in love with a common girl is unrealistic, but...did it ever happen in real life?

The "Cinderella" story is so prevalent in different cultures. In many versions, Cindy is actually of noble birth, but in other versions, she is a servant girl/slave.

Not sure of Wikipedia's accuracy but the Korean versian is WILD https://en.m.wikipedia.org/wiki/Cinderella

Anyway, why do you think Cinderella stories have always been so popular? And did a real-life Cinderella story ever occur in the medieval era - a nobleman marrying someone of common birth? Seems absurd with the rigid class structures, but stranger things have happened!