Why do people tend to stay in unhappy relationships?

Love is hard. Keeping a healthy relationship takes effort, but sometimes it’s just not possible. And when the moment to recognise a significant other might not be “The One” arrives, we’re reluctant to pull the plug. Why do we have such a hard time giving up on unhappy relationships when it’s sometimes clearly the best course of action?

The answer (and hear us out on this) might be economical. The sunk cost effect is “a tendency to continue an endeavour once an investment in money, effort, or time has been made”.[1] Examples of it are everywhere. Have you, for example, refused to drop a course you definitely don’t need to take because you’ve already put time into studying for it? Or have you decided to keep a shirt you don’t use anymore because of how expensive it was?

A perfect example of the sunk cost effect. Taken from Eduise

If you identify with any of these examples, you’ve been a victim of the sunk cost effect. And you’re not the only one; this phenomenon affects most people (even rodents!)[2] and it can be corrected if you know how to recognise it.[3] 

Anything you invest in becomes a sunk cost: money, time, effort, materials… anything you can’t get back, really.[1] Rationally, such expenses should not affect future decisions, but who said humans behave rationally?[4] The sunk cost effect is mostly brought up in economics because of the risk it poses for companies that keep throwing money into hopeless projects. Money is also the prime trigger of the effect since it’s easier to quantify.[5] On a personal level, however, the sunk cost effect can trick you into continuing doing things that make you unhappy. Since we don’t want you to be dissatisfied with your life choices (and partner), we will break the sunk cost effect down for you.

Why we like sinking ships

Two main reasons stand behind out enthrallment with sunk costs.

One of them is our impulse to recapture an investment’s value. If you spent resources on a project, you want to reap the benefits.[5] This desire originates from us wanting to justify our actions, but also from our reluctance to behaving wastefully. Humans are so waste-averse that we can stick to bad choices to avoid giving up on an investment.[5,6]

This is essentially how mental accounting works, except it’s in our minds. Taken from OFM Wealth

The second reason is the mental accounting model. This theory assumes our minds are banks. New project? Our brain opens an account and keeps tabs on all the resources we put into this project. And, as banks hate reporting losses, so does the human mind. We will keep a project going until we can at least neutralise any losses.[7,8] 

The power of sunk costs is such that it doesn’t even matter if you weren’t the one who invested. If someone gives you an expensive gift that you didn’t really like, for example, you’re probably still going to put in the effort to use it to make up for the cost.[9]

But where do relationships fit into all of this?

Sunk cost effect in love means staying in a relationship even though you’re unhappy. We’re not saying it’s the only thing involved in the decision; employment status, living conditions, even how many times someone has been divorced can lead to a break-up.[10,11] A lot of the reasons, however, may also count as sunk costs.[12] 

Ultimately, there can be no relationship without investment. We put in effort and time, plan dates, come up with romantic details, all for the sake of keeping the other person involved in the relationship.[13] We strive to generate commitment, and our own commitment is also a measure of satisfaction.[12] Whether we share assets with a partner can also influence the decision of staying in an unhappy relationship. Men, particularly, are affected by monetary sunk costs.[3]

According to Rusbult’s Relationship Investment Model, a number of components contribute to commitment.

Time is a big player, even more so than money. Generally, the longer you have been in a relationship, the harder it is to break up. And, unlike money, time isn’t so easily quantified.[5] We have to make an active effort to realise that a year together represents 365 days, or 31,556,950 seconds of being with that special person. That’s a lot of time. And science shows that the more time you invest, the less willing you are to end the relationship.[3]

Sunk costs have such an effect on relationships that it can even impact the beginning of one. Online relationships, for instance, show that the amount of time invested in setting up a dating profile, paying for a service, talking to the person, etc., can impact how much you are willing to commit to a date. Even if the person later matches with someone more suitable for them, they would still commit to the original date if they put enough effort into arranging it.[13]

Some dating apps charge up to $35 per month so it’s no wonder you’d be more committed to setting up dates with people you meet online if you’re paying that kind of money! Taken from Vice

The real danger of sunk cost

While sunk costs are not necessarily bad, they can entrap a person in an abusive relationship. Psychological entrapment (the decision to increase our commitment to a course of action to justify a bad choice)[11] is a form of  the sunk cost effect that places focus on the process of trying to make the endeavour succeed. Abuse victims may keep trying to make the relationship work, often wrongly blaming their own efforts for the failure of the relationship.[11] 

The sunk cost effect is powerful in relationships, but not enough to keep someone in a relationship that includes physical or sexual violence.[10] However, psychological violence is a different story. Victims of this type of abuse are vulnerable to psychological entrapment and may invest the same amount of time trying to save that relationship as they would with any other.[10] This can lead to a grave decline in their self-esteem and health

The Bottom Line

Knowledge is power. Now that you’re up to speed with the sunk cost effect and its associated risks, you can reduce the power it has over your decisions. Now, you can stop yourself from making a bad decision just because you put so much effort into it. Stop, think, and do the math to see what makes more sense. And if you, perchance, were looking for a sign to leave an unhappy relationship, this is it.

Academic References

  1. Arkes, H. R., & Blumer, C. (1985). The psychology of sunk cost. Organizational Behavior and Human Decision Processes, 35(1), 124–140.
  2. Sweis, B. M., Abram, S. V., Schmidt, B. J., Seeland, K. D., Macdonald, A. W., Thomas, M. J., & Redish, A. D. (2018). Sensitivity to “sunk costs” in mice, rats, and humans. Science, 361(6398), 178–181.
  3. Rego, S., Arantes, J., & Magalhães, P. (2018). Is there a Sunk Cost Effect in Committed Relationships? Current Psychology, 37, 508–519.
  4. Thaler, R. H. (2018). From cashews to nudges: The evolution of behavioral economics. American Economic Review, 108(6), 1265-87.
  5. Soman, D. (2001). The mental accounting of sunk time costs: why time is not like money. Journal of Behavioral Decision Making, 14(3), 169–185. 
  6. Arkes, H. R. (1996). The Psychology of Waste. Journal of Behavioral Decision Making, 9(3), 213–224.
  7. Soman, D., & Cheema, A. (2001). Marketing Letters, 12(1), 51–62.
  8. Thaler, R. H. (1999). Mental accounting matters. Journal of Behavioral Decision Making, 12(3), 183–206.
  9. Olivola, C. Y. (2018). The Interpersonal Sunk-Cost Effect. Psychological Science, 29(7), 1072–1083.
  10. Nunes-Costa, R., Serra, M., Sousa, T., & Leite, Â. (2019). Being psychologically abused is not enough into ending a relationship: Sunk cost effect in intimate abusive relationships. Revista Interamericana De Psicología/Interamerican Journal of Psychology, 53(3), 444–459
  11. Strube, M. J. (1988). The decision to leave an abusive relationship: Empirical evidence and theoretical issues. Psychological Bulletin, 104(2), 236–250.
  12. Goodfriend, W., & Agnew, C. R. (2008). Sunken Costs and Desired Plans: Examining Different Types of Investments in Close Relationships. Personality and Social Psychology Bulletin, 34(12), 1639–1652
  13. Coleman, M. D. (2009). Sunk Cost and Commitment to Dates Arranged Online. Current Psychology, 28, 45–54.

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