Everywhere in this world, if a girl reaches the age of 25, everyone starts to ask when she is planning to get married. If a girl passes the age of 30 without a husband, then wow! The situation gets worse, and society starts pointing out flaws in her character. What kind of world are we in?

They say a woman can't live alone, as if a woman is terribly reliant on a male till her death after 25! Why do they say that?
Why doesn't this society let a woman live alone as per her wish?