Robert Sternberg: Intimacy, Passion, Commitment, the Three Sides of Love

Who is Robert Sternberg?

Robert Sternberg was born on December 8, 1949, in Newark, New Jersey. He graduated from Yale, earned his PhD at Stanford in 1975, and spent most of his career at Yale, where he became a professor of psychology and education. He then held leadership posts at Tufts and Oklahoma State, and is now a professor of human development at Cornell University. He served as president of the American Psychological Association in 2003. He is best known for his work on intelligence, and love is his second big project.

In 1986, he published the triangular theory of love in Psychological Review, and it went on to become one of the most widely taught models in the world. He completed it with a measurement scale (1988, validated in 1997), then with a second theory, love as a story (1998), which he combined with the first in 2006 into a “duplex theory.” He has also written a great deal for the general public.

Why does this matter for your relationship? Because the triangle puts words on an intuition many people have but can’t put into words: you can love someone deeply and still be missing something specific. Naming that something, whether it’s intimacy, passion or commitment, completely changes the conversation.

The central idea

For Sternberg, love is made of three ingredients. Intimacy is closeness, warmth, trust, the feeling of being connected. Passion is physical attraction, desire, romantic drive. Commitment is, in the short term, the decision to love someone and, in the long term, the will to maintain that bond. How much love you have depends on the strength of all three. What kind of love you have depends on their balance.

The triangle is an image. Each side is an ingredient, and its shape tells you what your love looks like today. In a couple, there are two triangles, yours and your partner’s, and they never line up perfectly. For Sternberg, the gap between the two is a more common source of conflict than a lack of love itself.

The key concepts

The three components

They don’t move at the same pace. Passion rises very fast and falls back on its own, like getting used to anything. Intimacy grows with confidences and shared life, then can stall once you think you know everything about the other person. Commitment grows slowly and levels off, as long as it’s renewed. So when a couple settles in, passion drops without anything being wrong. What matters is what happens to the other two sides.

The seven kinds of love

By combining the three ingredients, Sternberg describes seven kinds of love (and an eighth, non-love, when none of them is present). Friendship (intimacy alone). Infatuation (passion alone, love at first sight). Empty love (commitment alone, the couple who stays out of duty). Romantic love (intimacy and passion, without commitment). Companionate love (intimacy and commitment, without passion, which describes many long-time couples). Fatuous love (passion and commitment, without intimacy, the whirlwind marriage). And consummate love, all three at once, which he considers possible but hard to maintain.

The ideal triangle and the real triangle

Each of us also carries an ideal triangle: the kind of love we would like to live. Sternberg reads satisfaction in the gap between the triangle you’re living and the one you want, and in the gap between the two partners’ triangles. Two people can have “just as much” love and still suffer because one wants more passion and the other wants more security.

The triangular scale

Sternberg’s scale has 45 statements, fifteen per component (“I feel close to…,” “I cannot imagine another person making me as happy…,” “I will stay with… through the difficulties”), rated from 1 to 9. A short fifteen-item version now exists, validated in 37 languages.

Love as a story

His second theory says that each of us lives our relationship as a character in a story, with a script in mind: the fairy tale, the business, the garden to tend, the journey, the war, the collection. He lists 26 of them. Two partners whose stories are compatible understand each other. Two incompatible stories produce conflicts that neither person can explain.

What the research says

The triangular theory is first of all a descriptive theory. What has mostly been tested is the measurement. Do the three components stand apart from each other, show up everywhere, and predict anything?

• Validation of the scale (Sternberg, 1997). Two studies find high reliability for each subscale and a three-factor structure consistent with the theory.
• An independent test (Acker and Davis, 1992). In 204 adults, the support is mixed. Commitment is much higher in married couples and is the best predictor of satisfaction, especially in long relationships. On the other hand, passion declines over time only in women, and intimacy does not decline as predicted.
• Universality (Sorokowski et al., 2021). In 7,332 participants from 25 countries on every continent, the scale measures the same thing everywhere, and the levels of the three components vary with relationship length in the predicted direction.
• The short version (Kowal et al., 2024). Fifteen items, validated in 37 languages, which make it possible to use the triangle in international surveys.

What this shows: three dimensions that turn up in every culture studied, and a commitment that weighs heavily in satisfaction. What it doesn’t show: that these three components are truly independent, or that the triangle explains why love changes.

Limits and criticisms

The main criticism is psychometric: intimacy, passion and commitment are very strongly correlated with each other in almost every study. When someone says they feel very intimate, they also say they feel very committed. You can read that as the mark of consummate love, or as a sign that the scale doesn’t distinguish well between things it claims to separate. Several items, in fact, fit another component better than their own.

The theory describes but doesn’t explain. It says nothing about the mechanisms: why passion wears off, how intimacy gets rebuilt, what keeps commitment going. Other authors in this section, Aron on novelty, Johnson on attachment, supply the gears the triangle leaves empty. And placing “consummate love” at the summit can make a happy companionate love look like a failure by comparison.

Finally, a note of honesty that concerns not his theory of love but his professional conduct. In 2018, Sternberg resigned as editor of the journal Perspectives on Psychological Science after colleagues criticized the publication, without peer review, of his own articles, with self-citation rates of 42 to 65 percent, and several texts were retracted for redundant publication. That doesn’t invalidate the triangle, which others have tested. It’s a reminder to read his numbers with the same critical eye as everything else.

How MyLoveLab uses it

The triangle is the underlying vocabulary of the Intimacy and desire dimension: telling an intimacy that has cooled from a passion that has worn out, and understanding that the second one fades without anyone being at fault. The commitment side feeds the Shared project dimension. Commitment isn’t only staying. It’s choosing again, and building something that makes it concrete.

We also borrow the idea of the two triangles, the lived one and the wished-for one, to read a satisfaction gap without looking for someone to blame. The test doesn’t calculate your “type of love.” It measures each side separately.

Further reading

• The Triangle of Love: Intimacy, Passion, Commitment · Book, 1988The general-audience book on the triangular theory, with the first version of the scale.
• Love Is a Story: A New Theory of Relationships · Book, 1998The 26 love stories: another way to understand why two partners don’t understand each other.
• Cupid’s Arrow: The Course of Love Through Time · Book, 1998How love begins, evolves and ends, read through the triangle.
• The New Psychology of Love · Book, 2006An edited volume with Karin Weis, in which Sternberg presents his duplex theory.
• A triangular theory of love · Article, 1986The founding article, in Psychological Review.

Frequently asked questions

References

1. Sternberg, R. J. & Grajek, S. (1984). The nature of love. Journal of Personality and Social Psychology, 47(2), 312-329.
2. Sternberg, R. J. (1986). A triangular theory of love. Psychological Review, 93(2), 119-135.
3. Acker, M. & Davis, M. H. (1992). Intimacy, passion and commitment in adult romantic relationships: A test of the triangular theory of love. Journal of Social and Personal Relationships, 9(1), 21-50.
4. Sternberg, R. J. (1997). Construct validation of a triangular love scale. European Journal of Social Psychology, 27(3), 313-335.
5. Lemieux, R. & Hale, J. L. (1999). Intimacy, passion, and commitment in young romantic relationships: Successfully measuring the triangular theory of love. Psychological Reports, 85(2), 497-503.
6. Sternberg, R. J. (2006). A duplex theory of love. In R. J. Sternberg & K. Weis (dir.), The New Psychology of Love. Yale University Press.
7. Sorokowski, P., Sorokowska, A., Karwowski, M. et al. (2021). Universality of the triangular theory of love: Adaptation and psychometric properties of the Triangular Love Scale in 25 countries. Journal of Sex Research, 58(1), 106-115.
8. Kowal, M., Sorokowski, P., Dinić, B. M. et al. (2024). Validation of the short version (TLS-15) of the Triangular Love Scale (TLS-45) across 37 languages. Archives of Sexual Behavior, 53(2), 839-857.

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