Let's take a look at the phrasal verb fall out. Like most phrasal verbs, it has more than one meaning. Here's how we can use fall out:
to fall - to separate. When one thing separates from another thing. In the cartoon the birds might separate from their nest (fall from the nest onto the ground), or you might fall out of your bed at night!
'When you get old your hair and teeth start to fall out.'
To fall out - to stop being friends with someone because you argued with them.
'I'm not speaking to Jean anymore. We fell out last week when she said she didn't like my new boyfriend.'
