Meaning of the word "why buy a cow when you can get the milk for free" in English

What does "why buy a cow when you can get the milk for free" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

why buy a cow when you can get the milk for free

US /waɪ baɪ ə kaʊ wɛn juː kæn ɡɛt ðə mɪlk fɔːr friː/
UK /waɪ baɪ ə kaʊ wɛn juː kæn ɡɛt ðə mɪlk fɔː friː/
"why buy a cow when you can get the milk for free" picture

Idiom

used to suggest that one should not commit to a serious relationship or marriage when the benefits of such a relationship are already available without it

Example:
He doesn't want to get married; he thinks, why buy a cow when you can get the milk for free?
They've lived together for ten years, so he figures, why buy a cow when you can get the milk for free?