Looking for a contractor

Welcome,

I'm hoping for some help, I was in a restaurant recently and there was a TV playing hits from the 70's and 80's. I forget who sang it and it was a duet between a black man and a black woman wearing green leggings or an outfit and they sang in English that she was unpredictable unattainable and so on, I don't remember the artist and title but something started with S.

If you are an expert of those years and are able to help me and give me at least clues or leads on performers of those years, black American who sang duets then thanks in advance. I know that it will be difficult to guess but maybe there will be a genius here who knows much better those performers from those years.... :)