Rose-Haired Sweetie

Western Animation

 * Princess Bubblegum of Adventure Time has many of these traits, except for the romantic part.
 * Aelita of Code Lyoko qualifies, being a genuinely sweet and good-natured person most of the time and while her love interest, Jeremie, doesn't have blue hair, he is associated with the color blue.
 * Steven Universe:
 * The aptly-named Rose Quartz has big, curly pink hair. She's often shown in flashbacks to have been very sweet and caring.
 * Pearl, who is depicted as a faded strawberry blonde in the present day, used to have brighter pink hair in her younger years before Rose Quartz met and married Greg, giving up her physical form to bring Steven into the world.