Why do we say "falling in love" instead of "rising in love"?

A human should control his mind in the sexual matters until he reaches a position. Only after reaching a suitable position he should think of a female partner only to marry. But situations never be favorable to all. Some people live according to the principles but some fails. When people unable to control their minds in this matter it is falling. That's why it is mentioned as falling in love. This is applicable to females too.