to become loose and drop; if soldiers fall out, they leave their lines and move away; to have an argument with sb so that you are no longer friendly with them; to stop being in love with someone
Oxford35% of films
to become loose and drop
Oxford24% of films
if soldiers fall out, they leave their lines and move away
Corporals, fall out!
Oxford12% of films
to have an argument with sb so that you are no longer friendly with them
Editorial6% of films
to stop being in love with someone
She's supposed to fall out of love with you.
Definitions from the Oxford Advanced Learner's Dictionary, 9th edition