Lulu is born with magical powers unassociated with any element (i.e. Light, darkness, wind, water etc.) and so all spells she performs ends in hazards. To prevent the school from judging her as an unfit magician and sealing her powers, she has to choose an element and a fellow magician to bond with.
Bring up a powerful magician in a school setting and get to know your fellow students, they are not only there to help you determine which sort of magic you should channel your powers into, but are also potential romantic interests that will bring you to your happy ending.