Answer:
actually you can phrase the question as: how did romantic ballet come out from classical ballet? as time went on, styles, fashions, etc changed. therefore the arts had to change as well. romantic ballet was the time in the 1800's when the costumes of the dancers were made more loose, thus allowing them more movement and easier. pointe work was made up and so was partner work. more challenging jumps and turns resulted as well. the idea of romantic was for the ballet to transport the audience into a world of fantasy. therefore the storylines turned "magical" and different as well. if you think about it, ballet and romantic ballet are very similar. it's called romantic ballet mainly because the 1800's was a time of great change for ballet.