Do Partners in Long-Term Relationships Understand Game Theory?

 With rising divorce rates worldwide, we often wonder what allows some couples to build lasting, fulfilling partnerships while others struggle. Although it’s unlikely that most couples consciously apply concepts from game theory, many seem to naturally act as “rational players” in ways that align with these principles, whether they realize it or not.

Game theory, at its core, is the study of strategic decision-making, exploring how individuals or groups make choices that impact one another’s outcomes. It helps explain not only competition but also cooperation, providing tools to predict behavior and reach mutually beneficial arrangements. In relationships, game theory can help illuminate why some partnerships succeed long-term by examining how people adapt their behavior in response to one another.

Nash Equilibrium in Relationships

One of the foundational ideas of game theory is the Nash equilibrium, a concept introduced by the Nobel laureate John Nash. Nash equilibrium represents a state where all “players” (or partners, in this case) have reached a balance. Neither partner benefits from changing their strategy on their own, meaning they’re both satisfied with the roles and contributions in their relationship. In simpler terms, each person’s choices reflect an understanding of their partner’s preferences, leading to a stable arrangement.

In a partnership at Nash equilibrium, both partners are content with their responsibilities and the dynamic they’ve built. For instance, each partner’s happiness might hinge on balancing shared responsibilities or supporting each other’s goals. Since both find value in the setup, neither feels a need to "deviate" by changing or seeking alternative arrangements, creating a naturally stable, fulfilling relationship.

Learning and Adjusting Strategies

In many real-life situations, including relationships, players tend to achieve equilibrium gradually. Through consistent interactions, they learn from each other's responses and fine-tune their behavior. Long-term relationships mirror this kind of repeated or “iterated” game, where each interaction represents a new “round” in which partners can refine their strategies. Rather than behaving impulsively, they become motivated to build trust and avoid actions that might damage the partnership.

For example, consider two businesses setting prices in competition. They might start by undercutting each other but eventually find a pricing balance where both can profit. Similarly, partners might begin with differing habits or expectations but learn to adjust, eventually creating a relationship dynamic that works well for both.

The Role of the Folk Theorem

Game theory’s Folk Theorem sheds additional light on long-term cooperation. This theorem states that in infinitely repeated games (like ongoing relationships), players can reach a wide variety of outcomes that support cooperation. Partners, aware of their ongoing commitment, tend to make choices that favor the long-term relationship’s health over short-term gains. This means they may even employ “punishments” if one partner acts against agreed values (e.g., withdrawing cooperation temporarily if a partner breaks a promise). The understanding that actions have future consequences encourages both to foster a balanced, trust-filled relationship.

Relationships as Iterated Games

Long-term relationships aren’t a one-off game; they’re a series of infinitely (daily) repeated interactions. Over time, this repetition encourages cooperation and deeper understanding. Couples find that nurturing kindness, trust, and communication brings them closer to their ideal “equilibrium,” minimizing friction and maximizing shared happiness.

In relationships, these principles come naturally. Partners may not consciously think about game theory, but by developing trust, adapting behavior, and investing in their relationship, they align their actions with these powerful strategies. So, while most couples probably don’t spend time studying Nash equilibrium or the Folk Theorem, the strategies they adopt reflect these principles in many ways.

Here’s to all who continue building strong, resilient partnerships—whether or not they know they’re using game theory!

The pictures in this post were taken from Unsplash.