There is an old animated film with a water nymph and a fire nymph that fall in love. It's one of those more serious cartoons where I think someone dies in the end.. but I can't be sure. The film had to be made some time in the seventies. It was kind of a romeo and juliet story but animated..

Can anyone help with a title?

Sea Prince and the Fire Child Shiriusu no densetsu (1981) (http://www.imdb.com/title/tt0203895/)