What song is it?!

[Chris]

Guys, I can't remind myself a song! I have some hints so maybe someone is able to help me

- it's very popular
- performed by man and woman (duet)
- I don't remember words. Probably there was something like "I don't know why/I don't know how/Please tell me how nanana "can't stop thinking"...
- they're singing rather simultaneously but in one moment woman's voice is getting stronger, she's almost shouting out one sentence;
- it was made in '60/'70/'80;
- very romantic, calm, voices are accompanied by quiet music in the background;
- it was probably used in a movie, they were singing, looking at each other eyes but maybe it's just my immagination

Any idea?

[Wardo94]

Movie, Grease?

[swalter]

Close my eyes forever by Lita Ford and Ozzy Osborne