The triangular theory of love is a theory about love created by Robert Sternberg. In relationships between people, the theory explains that love has three parts: intimacy, passion, and commitment.

Sternberg explains that intimacy means "feelings of closeness, connection, and being bonded to someone in a loving relationship." Passion refers to "the feelings and desires that lead to romance, physical attraction, and physical closeness in a loving relationship." Commitment has different meanings depending on time. In the short term, it means "the choice to love someone," and in the long term, it means "the promise to keep loving someone over time."

Components

Love can be understood through three main parts: intimacy, passion, and commitment. These parts work together in different ways as a romantic relationship grows over time. Relationships that rely on only one part are less likely to last than those that include two or all three parts. The total amount of love someone feels depends on how strong each part is, and the type of love someone feels depends on how each part compares in strength to the others.

The three parts of love are described as follows:

Intimacy is the part of love that connects people through closeness and understanding. This part involves knowing someone deeply and feeling close to them. It is mainly about personal, private moments and being familiar with someone.

Passion is the part of love that brings excitement and energy. This part includes feelings of romance and the desire for physical connection. It is mainly about strong feelings of enthusiasm or eagerness for something.

Commitment is the part of love that involves making decisions and staying together. This part includes promises to stay with someone and plan for the future. It is mainly about agreeing to do something and keeping that agreement.

Influences

Among the early ideas about love, two theories played an important role in helping shape Sternberg's model.

The first theory was created by Zick Rubin and is called The Theory of Liking vs. Loving. In this theory, Rubin explains that romantic love involves three key elements: attachment, caring, and intimacy. He says that if someone enjoys being with another person and spending time with them, they likely only like that person. However, if someone wants to be close to another person, values their needs as much as their own, and shares a strong emotional connection, they love that person. In Sternberg's model, intimacy is one of the main parts of love, showing that it helps explain the difference between caring love and intense love.

The second theory was created by John Lee and is called the color wheel model of love. Lee compares love to the primary colors red, blue, and yellow. He says there are three main types of love: Eros (passionate love), Ludus (playful love), and Storge (familial love). Lee explains that these three types can be combined, like mixing colors, to create other forms of love. Sternberg's model also uses the idea that combining his three main parts—intimacy, passion, and commitment—creates different kinds of love.

Sternberg also studied three other models of love: the Spearmanian, Thomsonian, and Thurstonian models. The Spearmanian model says love is one single feeling made up of many positive emotions. The Thomsonian model says love is a mix of different feelings that together create the feeling of love. The Thurstonian model is similar to Sternberg’s triangular theory. It suggests love is made of several feelings that are all important but should be understood separately. In this model, these feelings work together but can also exist on their own.

Elaboration

Sternberg's triangular theory of love was created after discovering passionate love and companionate love. Passionate love focuses on the present when a relationship begins, while companionate love lasts and becomes stronger over time with deep meaning in the relationship. These are different types of love but are connected in relationships.

Passionate love is linked to strong feelings of love and wanting to be close to a specific person. This love is full of excitement and new experiences. Passionate love is important at the start of a relationship and usually lasts 3 to 12 months. It involves chemicals in the brain, such as phenylethylamine and oxytocin, which increase during this time. Research has shown that love is also connected to the brain's opioid circuit. These feelings are most common in the earliest stages of love.

Companionate love comes after passionate love. It is also called affectionate love. When a couple reaches this level, they feel understanding and care for each other. This love is important for a relationship to last. It develops later in a relationship and needs both people to know each other well.

Sternberg created his triangle with three parts: intimacy, passion, and commitment.

Intimacy is the part of the triangle that includes the close connections in loving relationships. When two people feel intimacy, they respect each other, want to make each other happy, share things, communicate, and help when needed. People with intimacy deeply value each other. Intimacy is called "warm" love because it brings people close. Sternberg thought intimacy might decrease in long relationships, but later studies showed this was not true.

Passionate love is based on strong desire. Couples in passionate love feel physically attracted to each other. Sexual desire is often part of this love, but it also includes feelings like caring, sharing power, and growing as individuals. Passionate love is called "hot" love because it includes strong physical excitement. Sternberg believed passionate love might decrease as other forces in a relationship take over, based on Solomon's opponent-force theory. However, this was only found to be true for women in some studies.

Commitment, or committed love, is when people stay together for a long time. It is possible to be committed to someone without feeling intimacy or passion, and to feel intimacy or passion without being committed. Commitment is called "cold" love because it does not require intimacy or passion. Sternberg believed committed love becomes stronger as a relationship grows. Commitment can also be found in friendships.

Sternberg believed love develops in predictable ways, with all couples experiencing intimacy, passion, and commitment in the same order.

Although these types of love may have some qualities found in non-loving relationships, they are unique to loving relationships. Non-love is described below, along with other types of love. These types of love are combinations of one or two parts of Sternberg's triangle.

Forms of love

The three parts of love are shown on the corners of a triangle. These parts work together and with the actions they create to form seven different types of love (non-love is not shown). The size of the triangle shows how much love there is—the bigger the triangle, the more love there is. Each corner of the triangle represents a different kind of love and helps create different combinations of love. The shape of the triangle shows the "style" of love, which can change over time in a relationship:

• Non-love: No parts of love are present. There is no connection, and the people involved do not care about the relationship.
• Liking/friendship (Intimacy): This is a positive connection with someone without romantic feelings, such as friendships or being familiar with someone.
• Infatuated love (Passion): Also called "puppy love," this is when someone has romantic feelings but has not yet formed a close connection with the other person. Romantic relationships often begin this way and may grow into romantic love as closeness develops. If intimacy or commitment does not grow, this type of love may end suddenly.
• Empty love (Commitment): This happens when there is commitment but no romance or understanding. In some arranged marriages, the relationship may start this way and later change into another type of love.
• Romantic love (Intimacy & Passion): This includes both closeness and romantic feelings, such as in a romantic relationship or a short-term romantic encounter.
• Companionate love (Intimacy & Commitment): This is a long-term, positive connection without romance, often seen in long-term marriages where passion is no longer present. It is also common in close friendships or family relationships.
• Fatuous love (Passion & Commitment): This is a long-term romantic relationship without a close connection. Marriages in this category often lack stability and can become unsatisfying.
• Consummate love (Intimacy, Passion, & Commitment): This is the most complete form of love, including all three parts. It is considered the ideal relationship in the model. Sternberg suggests that couples with this type of love may continue to have a strong relationship for many years, feel happy with no one else, and work through challenges well. He also warns that keeping this type of love may be as hard as creating it. He emphasizes the importance of showing love through actions. "Without expression," he says, "even the greatest love can fade."

Sternberg’s triangular theory of love helps explain his later theory called Love as a Story. In this theory, he explains that different love stories show how people understand love. Over time, these stories help people decide what love means to them. These two theories together form Sternberg’s duplex theory of love.

"Relationships that last the longest and are most satisfying are those where partners work to keep closeness and strengthen their promises to each other."

Support and criticism

In a study conducted by Michele Acker and Mark Davis in 1992, Sternberg's triangular theory of love was tested for correctness. By examining people outside the usual group of 18- to 20-year-old college students, Acker and Davis were able to study love stages more accurately. Some criticism of Sternberg's theory is that although he described the stages of love, he did not explain when these stages might change during a relationship. He also did not clarify if the parts of love depend on how long a relationship lasts or on the stage it has reached. Acker and Davis noted that the stage and length of a relationship could be important to understanding love and explored these factors.

They found that there are no clear answers because each couple and each person in a couple may experience love differently. There are three ways people can view Sternberg's triangular theory of love, or "the possibility of multiple triangles." These triangles exist because individuals may feel each part of love (or each corner of the triangle) more strongly than others. These separate triangles, as explained by Acker and Davis and others, are called "real" triangles, "ideal" triangles, and "perceived" triangles.

"Real" triangles show how each person sees the progress and depth of their relationship. "Ideal" triangles show what each person believes their partner or relationship should be like. "Perceived" triangles show what each person thinks their partner believes about the relationship. If any of these three triangles do not match between partners, dissatisfaction may increase.

Love may not be as simple as Sternberg's triangular theory suggests. Sternberg tested his theory on couples of similar ages (average age 28) and with similar relationship lengths (4 to 5 years). His sample had limited variety in characteristics. Acker and Davis pointed out this issue as one of three major problems with Sternberg's theory. Romantic love, in particular, often differs between undergraduate couples and couples who are not undergraduates. Acker and Davis studied a group older than Sternberg's undergraduate sample. Sternberg himself addressed this in 1997.

The other two major problems with Sternberg's theory are the question of whether the levels of love are separate from each other and the question of how the levels of love have been measured. These issues continued to be studied, for example by Lomas in 2018.

In a large study published in the Journal of Sex Research in 2020, the cultural universality of the theory was supported.