The song is a duet from the 1950 musical, Guys and Dolls, and is sung by the characters Sky Masterson and Sister Sarah Brown. In the play it immediately follows the short solo song "My Time of Day", sung by Sky. Both songs were omitted from the 1955 film adaptation of the musical, and replaced by the duet "A Woman in Love".
I've never been in love before Now all at once it's you It's you forever more.
I've never been in love before I thought my heart was safe I thought I knew the score
But this is wine that's all too strange and strong I'm full of foolish song And out my song must pour
So please forgive this helpless haze I'm in I've really never been In love before.