Princess Bubblegum

Princess Bonnibel "Bonnie" Bubblegum of the Candy Kingdom (also known as: PB; Peebles; P-Bubs; Bonnie), is a fictional character in the American animated Cartoon Network television series "Adventure Time", created by Pendleton Ward.
Princess Bubblegum is the current incarnation of the Candy Elemental. She is the ruler to the inhabitants of the Candy Kingdom, who are all composed of types of desserts and candies. 
Princess Bubblegum rules over the Candy Kingdom, but in the Season 6 episode "Hot Diggity Doom" (the first part of the season's finale), an election was held and she lost to the King of Ooo by a landslide. 
As a result, she no longer ruled the Candy Kingdom and the King of Ooo replaced her as the new ruler, until a rebellion against King of Ooo allowed her to reclaim the throne in "The Dark Cloud".
In an interview, Olivia Olson (who voices Marceline) stated that Marceline and Bubblegum are ex-girlfriends. In the series finale "Come Along with Me", Marceline and Bubblegum share their first onscreen kiss, confirming mutual romantic feelings between them and become girlfriends.