Boy meets girl.
Boy falls for other girl.

'boy' and 'girl' are countable nouns, aren't they?
Grammar books explain that a countable noun always takes either the indefinite (a, an) or definite article (the).
They need the article 'a', 'the' or plural forms, don't they?
You know, You often see "Boy meets girl" in the titles of novels and movies etc.
I wonder why underlined words are without the aricle.