Meaning of "two out of three ain't bad"
In this song's lyrics, I cannot understand the phrase "two out of three ain't bad" :
...
I want you, I need you
But there ain't no way I'm ever gonna love you
Now don't be sad
'Cause two out of three ain't bad.
...
- I want you.
- I need you.
I love you.
That's two out of three. Which is better than one out of three, or even zero out of three. So, according to the author, the person whom the song is dedicated to shouldn't be sad that they are not being loved. It could be worse.