A Game Theory Analysis of Infidelity

As a mythical-obviously-made-up writer once said ‘We don’t choose our topics, our topics choose us’.  So without further ado, let’s get on with understanding what this article is all about.

Game Theory is described as “the study of mathematical models of conflict and cooperation between intelligent rational decision-makers.”  Given the practical role Game Theory has played in a number of fields – economics, political science, and psychology, as well as logic, computer science, and biology – can it perhaps teach us something about relationships, trust and infidelity?

Before we answer that, let’s skim through the basics of Game Theory using a popular model – The Prisoner’s Dilemma.

The Prisoner’s Dilemma

Two criminals (let’s call them Dapo and Chima) are arrested for a crime carrying a penalty of six years in prison. They are held in separate rooms, and cannot communicate.

If they cooperate with each other and both remain silent, they will only have to serve one year each as there will be too little evidence to convict them of the more serious charges.

If they give evidence against each other they will each get three years each in prison.

However if only one prisoner talks, that prisoner will go free as a reward, while their betrayed accomplice will then have to serve five years. 

We’ve all seen different versions of this scenario in movies and crime shows.


When interrogated: Chima stays silent Chima betrays Dapo
Dapo stays silent Each serve one year Dapo serves five years, but Chima goes free
Dapo betrays Chima Chima serves five years, but Dapo goes free Each serve three years


As the outcomes show, each person gains more from confessing when the other person remains silent. So if both prisoners do not trust each other, both prisoners will most likely betray each other by confessing, and consequently get the full penalty of three years each. This outcome is also known as a Nash Equilibrium. (RIP to the brilliant John Nash who passed away last month)

This unfavourable outcome would’ve been avoided if they both cooperated; they would’ve both kept quiet and gotten the lowest sentence – a year each. However, mutual cooperation is only guaranteed when both prisoners undoubtedly trust each other to cooperate and keep silent – otherwise someone gets betrayed or they both end up in prison with maximum penalty.

The lesson? Cooperation is key to the benefit of all, but it doesn’t just happen. Trust has to exist for both prisoners to cooperate.

At the core of the prisoner’s dilemma is the idea of ‘trust’ versus ‘mistrust’. Trust is key to the success of all forms of relationships, as you’ll see when we apply this model to infidelity.


Prisoner’s Dilemma Model of Infidelity

People cheat for different reasons – good old ‘woman-wrapper’ behaviour, retaliation, jealousy, insecurity and the overused ‘the devil made me do it’ reason. For this model, we’ll stick to those who cheat or refuse to cheat due to their anticipation of their partner’s decision to do likewise. 


In a relationship He Does Not Cheat He Cheats
She Does Not Cheat They both do not get hurt She gets hurt
She Cheats He gets hurt They both hurt each other


When Trust is Certain

In cases where one cheats, the other partner gets hurt and when both cheat, both get hurt. When any partner is selfish, the relationship suffers. When both trust each other and do not cheat, no one gets hurt and they both achieve their common goal of remaining together in a healthy relationship.


Hedging – When Trust is Uncertain

With relationships, trust wanes and trusts grows. In periods when trust may wane and in anticipation of wrong action from their partner, some hedge to protect themselves. Hedging refers to when an individual keeps another person on the side as a backup in case the partner cheats and the relationship fails. In Nigeria, we refer to this person as a ‘side-chick’ or a ‘side-guy’.

Note that this is one of several reasons hedging happens. Other reasons for the need of a side-chicks or guy other than hedging could be financial or romantic.

If both individuals trust each other, they have no reason to hedge with a different partner or doubt that their partner cheated on them, thereby nullifying the need for all the games. However, in reality, cheating happens irrespective of action of the other partner, so hedging is in fact still needed.


Pre-emptive Cheating – When Trust is Absent

Pre-emptive cheating takes the act of hedging one step further and engages. For example, if Russia anticipates that America’s gonna nuke it, Russia will act first and nuke America. Same scenario as a woman who cheats in anticipation of her man cheating on her. In essence, your fear of what your partner might do will lead you to do likewise. Sounds like a Nollywood script, but these things do happen.

This article might sound too theoretical, but there is a practical lesson here. If you care about your relationships, do your best to preserve mutual trust. Once trust is lost, all bets are off.

Trust isn’t the only factor needed to guarantee a successful relationship or agreement, but evidence of trust goes a long way to ensure that people don’t take selfish decisions that only benefit themselves. The same applies in other areas such as business or politics.

However, there are some cases where people will always put their self-interest above you or the relationship, trust be damned. Do yourself a favour and stop being their prisoner.


  • donp

    fantastic… I’m gonna rewrite this just so you know i didn’t steal this. lol.

  • Dami

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  • Chibunnam

    This is really really good..