August 17, 2026, 9:39 am | Read time: 3 minutes
A French mathematics professor claims to have discovered when a relationship will last–and when it will fail. His formula takes into account feelings of love, habituation, crises, and even infidelity.
The Love Formula Aims to Explain Relationships
Laurent Pujo-Menjouet believes that the dynamics of a relationship can at least partially be described mathematically. In his book “Love! Valour! Equations!” the French professor uses differential equations to try to predict the development of feelings of love.
At the center is an equation where P(t) represents a partner’s feelings of love. It considers factors such as the habituation effect, as well as positive and negative events. The birth of a child, a promotion, financial problems, a death, or an affair can significantly change the relationship. It is also crucial how the partner reacts to such events–for example, with an apology or a loving gesture.
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Mathematics Reaches Its Limits
If the feeling of love in Pujo-Menjouet’s model falls below a certain threshold, the end of the relationship is imminent. However, experts warn against viewing the formula as a reliable love oracle. Mathematics professor Rebecca Tyson emphasizes that human social behavior is extremely complex and can never be fully captured by a model.
Psychologist Guy Bodenmann from the University of Zurich also sees limitations. Even if psychological research identifies typical patterns in couples, the individual course of a relationship cannot be reliably predicted. Some couples are even satisfied shortly before a divorce. Additionally, factors such as education, religion, financial dependency, or personal environment play a role. In Germany, a marriage lasts on average about 14 years.
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The Kiss Reveals More Than Any Equation
Psychotherapist David Wilchfort is skeptical of the idea that feelings in a relationship decrease according to a fixed mathematical pattern. In his practice, he experiences that feelings can shift between closeness and distance in a very short time. What is crucial is the inner attitude toward the partner: Is it still important to both that the other is doing well?
Psychotherapist Wolfgang Krüger sees it differently. He is more open to the mathematical approach and refers to the couple research of John and Julie Gottman, who examine the stability of relationships based on certain behaviors. His own surprisingly simple indicator: the kiss. Krüger asks couples if they still kiss–and how. In his experience, this can reveal quite well how much closeness still exists between two people. Love remains complicated. Yet it seems to be somewhat predictable.