One of my favorite things about Miyazaki's movies is the romance between the characters. You can always tell that their is a spark between the main female and male character and its great to see how their friendship deepens throughout the movie.
Princess Mononoke:
San and Ashitaka
Castle in the Sky
Sheeta and Pazu
Spirited Away
Chihiro and Haku
Kiki's Delivery Service:
Kiki and Tombo