The investment model1 offers an elegant explanation for why we sometimes find it very difficult to leave a relationship, even when relationship satisfaction is persistently low. This model posits we are likely to remain in a relationship to the extent that we feel dependent on that relationship. This dependence, in turn, leads to greater commitment to remaining in the relationship over time.

While we do tend to feel more dependent in satisfying relationships, even in an unsatisfying relationship dependence can be present when:

  • We are highly invested in the relationship, i.e. we have put a great deal into the relationship that would be lost if it ended. Sunk cost fallacy – which describes our tendency to persist in certain endeavors that we have invested resources (time, money, effort) into even when the net present value of future costs outweigh benefits – certainly comes into play here.
  • We see few appealing alternatives to the relationship (such as other viable partners in the dating pool). Note that the relative appeal of alternatives may be subject to the endowment effect – our tendency to place a higher value on something that we already have than the value we would place on that same thing if we did not already have it (the “fair market value” if you will, though that term makes more sense in economics than in relationships!).

Several studies support this model. For example, a meta-analysis of 202 studies (N = 50,427) found that alternatives and investment emerged as independent predictors of commitment, above and beyond relationship satisfaction.2 Commitment, in turn, is a strong predictor of choosing to remain in the relationship.3

Outside of the investment model, researchers have also demonstrated that, in hypothetical contexts, we are hesitant to end a relationship even when attractive alternatives are available.4 In a set of vignette studies, subjects were asked to choose between staying in a 3-month-long relationship or leaving to date a more attractive partner. Subjects showed a statistically significant bias towards maintaining the current relationship. Concerns about hurting the current partner and uncertainty surrounding the alternative relationship are possible explanations for this result. This could be interpreted as evidence for loss aversion or the status quo bias – our preference for the current state of affairs even when a switch would in expectation be advantageous. Or it may just be that age old saying in action: a bird in the hand is worth two in the bush.

Of course, there is a more humanistic view of why whether to stay in a relationship or leave it is a tough call, and I will examine this in my next post on hard choices.

  1. Drigotas, S. M., Rusbult, C. E. (1992). Should I stay or should I go? A dependence model of breakups. Journal of Personality and Social Psychology, 62, 62–87. Google Scholar ↩︎

  2. Tran, P., Judge, M., Kashima, Y. (2019). Commitment in relationships: An updated meta-analysis of the Investment Model. Personal Relationships, 26, 158–180. Google Scholar ↩︎

  3. VanderDrift, L. E., Agnew, C. R., Wilson, J. E. (2009). Nonmarital romantic relationship commitment and leave behavior: The mediating role of dissolution consideration. Personality and Social Psychology Bulletin, 35, 1220–1232. Google Scholar ↩︎

  4. Gunaydin, G., Selcuk, E., Yilmaz, C., Hazan, C. (2018). I have, therefore I love: Status quo preference in mate choice. Personality and Social Psychology Bulletin, 44(4), 589–600. Google Scholar ↩︎