We've all been there, stuck in a relationship that wasn't the best for us but for some reason we stayed.

Many people break up with their significant other and after all the tears and healing has taken place, they begin to wonder why they stayed with that person for so long. According to Stylist, the reason why many of us stay in the relationship even though we're not necessarily 100% is because of something called the 'sunk cost effect'. Psychologist Sarah Rego has said that this theory means that because you've invested so much into the relationship, you're going to want to continue investing in it. In Portugal, at Minho University, Rego and two colleagues asked 1,000 participants of a study about this 'sunken cost effect'. The study presented people with hypothetical situations with their other half and asked what they'd do in certain situations. The subjects were divided into 4 groups, and everyone was asked what they'd do if trapped in a sexless and unhappy marriage. The first group were only told they were in a loveless marriage, the second group were told they were married for a year, the third were told they had bought a house with their spouse and the last group were told that they had put a lot of effort into trying to fix the marriage. Results from the study found that 35 percent of people who had invested money and effort would stay their spouse, while 25 percent of people admitted they'd leave a marriage if it was still new and if they hadn't put in much effort. The authors of the study said sometimes people are committed to a relationship because of money, time and effort rather than love.

"Together... 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."