The #1 Reason People Stay In Unhappy Relationships, According To Science

In a world that is dominated by romantic comedies and fairy tales, many of us grow up dreaming of finding the love of our lives, vowing to not stop until we find the perfect partner. While many people are lucky enough to find their perfect match, we all know somebody who has been in an unhappy relationship or worse, somebody who feels trapped in an unhappy relationship.

While there are often a number of factors at play when it comes to a couple being unhappy in their relationship, it can sometimes be easy to look at a relationship from the outside and as an onlooker, simply just not be able to understand why this couple doesn’t just end things now. If they’re really that unhappy, why are they still together?

Looking to answer this question, a new study discusses a factor called the “sunk cost effect.” The study that was published in Current Psychology found that even when people are unhappy in a situation, the sunk cost effect causes them to remain in that situation because they simply feel as though they have invested too much in the relationship to move on.

“The sunk cost effect occurs when a prior investment in one option leads to a continuous investment in that option, despite not being the best decision,” the study noted.

Psychologist Sara Rego, along with her colleagues at the University of Minho in Portugal, ran two experiments that asked participants if they would remain in a hostile, sexless marriage based on different variables. The first variable was time (a 1-year marriage instead of 10), a second variable was effort (they had invested a significant amount of effort in trying to improve the relationship), and a third variable was money (they had purchased large items with their partner that would make splitting up difficult). There was also a control group who did not have any variables.

In the end the study found that 25 percent of people from the time group said they would stay in the marriage, while 35 percent in the money and effort groups said that they would stay in the marriage.

“[These] experiments confirmed the initial hypothesis that investments in terms of time, effort, and money make individuals more prone to stay and invest in a relationship in which they are unhappy,” wrote the authors of the study.

Read next: This Is The #1 Thing That Happy Couples Do To Maintain Their Relationship