Letting Go of the Past: How the Sunk Cost Fallacy Affects Relationships

Monday, November 11, 2024.

Part of human experience is investing our time, energy, and love into building a meaningful connection with our partner.

This investment is part of what makes long-term relationships so precious, but it can also create a trap known as the "Sunk Cost Fallacy."

This psychological concept explains why people sometimes stick with decisions, behaviors, or relationships simply because they’ve already put so much effort into them — even if they’re no longer beneficial.

In couples therapy, exploring the Sunk Cost Fallacy can help partners see when past investments might be preventing them from making positive changes.

Understanding the Sunk Cost Fallacy

The Sunk Cost Fallacy is a cognitive bias that causes people to continue a behavior solely because of previous investments of time, money, or effort, rather than evaluating if that behavior still serves their best interests (Arkes & Blumer, 1985).

It’s the reason we sometimes finish a book we’re not enjoying, stay in a job that drains us, or keep items we no longer use.

When applied to relationships, this fallacy can show up when couples continue harmful dynamics simply because they’ve “put so much into this relationship.”

In the context of a partnership, the Sunk Cost Fallacy can be especially challenging.

For example, couples may avoid addressing conflict because they’re used to keeping the peace or might keep silent about their needs to avoid disrupting a comfortable routine. Conflict Avoidance is an admirable couple style, but failure to clarify boundaries can lead to meaningless suffering for both partners.

Over time, these habits can lead to resentment and dissatisfaction, yet breaking them can feel intimidating because so much has already been invested in maintaining the status quo.

How the Sunk Cost Fallacy Can Affect Relationships

Avoiding Conflict for the Sake of “Peace”: Many couples avoid tough conversations to maintain a sense of harmony.

While this may seem like a way to protect the relationship, research by Gottman and Silver (1999) shows that conflict avoidance often leads to “stonewalling” — shutting down or withdrawing emotionally — which can harm relationship satisfaction.

• Sticking with Ineffective Communication Patterns: Some couples simple continue, year after year, with communication habits that feel comfortable, even if they’re not effective.

• For example, partners might rely on silent treatments or passive communication because they’re familiar. However, research shows that these patterns, while comfortable, can erode trust and emotional intimacy over time (Markman, Stanley, & Blumberg, 2010).

• Ignoring Personal Needs to Maintain Stability: Some partners may avoid voicing their needs to avoid “rocking the boat.”

• While it’s normal to compromise in relationships, consistently sacrificing personal needs can lead to burnout, resentment, and diminished well-being. A study on marital satisfaction found that mutual respect for individual needs is essential for long-term satisfaction (Karney & Bradbury, 1995).

Tips for Letting Go of the Sunk Cost Fallacy in Relationships

• Recognize That Past Investment Doesn’t Dictate the Future: Just because a certain dynamic has been in place for years doesn’t mean it has to stay that way. Partners can embrace change as an opportunity to build a stronger, healthier connection.

• Focus on What Benefits the Relationship Today: Therapy can help couples identify what behaviors support their relationship in the present, not just what they’ve been doing out of habit. By shifting the focus to positive, beneficial actions, couples can feel more empowered to make changes.

• Accept Discomfort as Part of Growth: Trying new approaches — like setting boundaries or addressing long-avoided issues — may feel uncomfortable at first. Research shows that growth in relationships often requires a willingness to face temporary discomfort in exchange for long-term satisfaction (Karney & Bradbury, 1995).

Breaking Free from the Sunk Cost Trap

In couples therapy, the Sunk Cost Fallacy offers a helpful way to explore how past habits might be limiting growth. It would profit us all to recognize and understand this bias.

When that happens, partners might begin to make choices based on what’s truly beneficial rather than what’s familiar.

Together, they can take small steps toward a relationship that prioritizes healthy, supportive behaviors over past investments, creating a dynamic that serves them both as individual partners and as a couple.

Be Well, Stay Kind, and Godspeed.

REFERENCES:

Arkes, H. R., & Blumer, C. (1985). The psychology of sunk cost. Organizational Behavior and Human Decision Processes, 35(1), 124-140.

Gottman, J. M., & Silver, N. (1999). The Seven Principles for Making Marriage Work: A Practical Guide from the Country's Foremost Relationship Expert. Harmony Books.

Karney, B. R., & Bradbury, T. N. (1995). The longitudinal course of marital quality and stability: A review of theory, method, and research. Psychological Bulletin, 118(1), 3-34.

Markman, H. J., Stanley, S. M., & Blumberg, S. L. (2010). Fighting for Your Marriage: A Deluxe Revised Edition of the Classic Best-seller for Enhancing Marriage and Preventing Divorce. Jossey-Bass.