Ela era controlada por um chip de controle mental das sortes.
Do wiki:
Gideon's Microchip is a device seen only in Scott Pilgrim vs. the World as a mind control device used on Ramona to follow Gideon's commands whenever he's around (Breaking up with Scott, Telling Scott that she was still with Gideon, etc.) and keeps her docile during Gideon's first fight against Scott in the movie. It is implanted on the back of her head and glows green when active.