Wanderings- Santos 06 janeiro

Today I pondered flight and gravity as the song by B.O.B came on. "what goes up must come down, don't let me fall". But then why is the expression "fall in love" and not "fly in love"? Maybe it has to do with the earth and her pull...gravity - causing you to fall. The expression puzzles me because when I feel love, I feel like flying - not like I'm falling.