Robert Sternberg (Bennett, 1985) at Yale has a theory that there are three components to love: (1) Intimacy = baring souls, sharing, liking, and bonding (a slowly developing emotional-interpersonal involvement, as in a friendship). (2) Passion = sexual attraction (an instant or quickly developing motivation or addiction which usually declines over the years to a stable level). (3) Commitment = stable, dependable devotion (a slowly developing cognitive decision to stick by the other person in bad times, as in a marriage). Different mixtures of these three parts determine what kind of love it is, e.g.:

Notice that "romantic love" involves talking, sharing, and closeness (intimacy) and touching, kissing, etc. (passion) but not an agreement to stay with the other person if the friendship and passion decline sharply (commitment). Likewise, "companionate love" lacks passion and fatuous love lacks deep personal enjoyment of each other as people. There is nothing missing in consummate love, so wouldn't everyone want to have and get that kind of love? It is most peoples' ideal, but it is hard to achieve. Fortunately, love doesn't have to be that intense all the time.

A good-to-acceptable arrangement, according to Sternberg, is when both partners want, receive, and give the same amounts of the three ingredients, i.e. they both have the same kind of love in about the same intensity. However, as the partners' three dimensions of love differ more and more from each other, especially in terms of total investment, the quality of the love relationship deteriorates. For example, within limits, partner A can be primarily interested in sex (passion) while partner B is more interested in love (intimacy), providing both A and B are devoted to each other. But there are three threats to the relationship: if A loses sexual interest or B falls out of love or if either decides to "look around" for the ingredient they aren't getting. The less we get of what we want, the more unhappy we become.

Sternberg says divorces occur not because we make mistakes and chose the wrong partner but because the partners' needs change over time. That is, many people who get divorced may have made a very understandable choice at the time. They just didn't accurately estimate the future changes in their loves and in their needs for love. He found the qualities that often increase in importance as a relationship matures are: sharing values and religious beliefs, willingness to change to accommodate the partner, and tolerance of the other's faults. Qualities of lessening importance over time are: interesting personality, attentiveness, and relationship with in-laws. Qualities of varying importance over time are: sexual attractiveness, skills at making love, ability to empathize, willingness to express feelings, and similar intelligence. The problem is to predict what qualities will be most important in your relationship in the distant future and how you and your partner will measure up on those traits. This is a very difficult task. But thinking in terms of these three dimensions may help you assess where you are now and what your relationship will be like in the future.

Brehm (1985) believes there are basically only two types of lovers--romantic (passionate) and best friend (companionate). Most love relationships, she thinks, are a mixture of both types. Romantic love is intense, sexual, and frantic (e.g. strong efforts to win and hold on to the affection). In contrast, companionate love is calmer, involves more relaxed love making and is based on respect, trust, and security as friends. Romantic love is what is measured on Rubin's (1973) Loving Scale and best friend love is measured on his Liking Scale. Using these two scales and measures of romanticism, it has been possible to study the differences between males and females.