" In psychologist Robert Sternberg's triangular theory of love, he identifies three characteristics: passion, intimacy, and commitment. Passion is defined as physical attraction and sexual connection, intimacy as the sense of being close and bonded, and commitment as the decision to be together exclusively. As a romantic relationship moves through time, one of these three characteristics is carrying the most weight. Accordingly, although romantic love offers both intimacy and passion/sex, commitment is needed to complete the triangle. "

― Susan Shapiro Barash , The Nine Phases of Marriage: How to Make It, Break It, Keep It