Not all Disney movies have a duet between the leads. I wish they all did. They're usually the most magical part of the film.
Snow White and the Prince, Wishing/One Song.
Cinderella and Charming, So This is Love.
Aurora and Philip, Once Upon a Dream.
Jasmin and Aladdin, I Can Show you the World.
Rapunzel and Eugene Fitzrupert, I Can See the Light.
Go see Tangled. It was classic Disney in so many ways and the CGI was stunning. It reminded me of The Ordinary Princess and Book of a Thousand Days, two of my favorite books, as well as The Princess and the Pauper (that epic Barbie movie) Ever After. It was lovely.