Love can be characterized by passion, caring, intimacy, and commitment. Elements of romantic love include attachment, caring for the other person's happiness as much as your own, and sharing private thoughts and feelings. Rubin developed scales to measure liking and loving as a way to assess attitudes toward others and measure the complex feeling of love. Sternberg's triangular theory of love identifies three components - intimacy, passion, and commitment - that characterize different types of love such as infatuated love, empty love, companionate love, fatuous love, and consummate love. Maintaining consummate love, which represents the ideal relationship, may be difficult.