Although the cliché "opposites attract" is often heard, long-term psychological research actually shows that similarity and shared meaning are the main foundations of lasting relationships.
Here is a psychological breakdown of why the absence of these two elements often causes relationships to fail:
1. The Role of Similarity: The Similarity-Attraction Effect
In social psychology, there is a strong principle called the Similarity-Attraction Effect. We are naturally drawn to and feel safe with people who are similar to us. However, psychologists distinguish "similarity" into two levels:
- Surface-Level Similarity: Hobbies, music tastes, or favorite foods. Differences here are not fatal. You can like rock music and your partner jazz, and the relationship can still work.
- Deep-Level Similarity: Core life values, spiritual views, money management, parenting styles, and future vision.
Why does this cause failure?
If you lack deep-level similarity, constant cognitive conflict will occur. Every major decision—from buying a house to communicating—becomes a battlefield because your "life dictionaries" are different. Without a shared value foundation, compromise becomes extremely tiring and often feels like a sacrifice of self.
2. Sternberg's Love Theory: The Loss of "Commitment"
Robert Sternberg, a renowned psychologist, formulated the Triangular Theory of Love. According to him, complete love consists of three components:
- Intimacy (emotional closeness)
- Passion (physical desire)
- Commitment (the decision to stay together)
When you say "there is no reason to be together," in this psychology, it is often translated as the loss of the Commitment component.
- Without a strong reason (shared vision), the relationship only survives on Passion (which is temporary by nature) or Intimacy (merely being a confidant).
- When desire fades (a natural process), it is the "reason" or commitment that holds partners together through difficult times. If that reason is absent, there is no "glue" to bind the relationship when storms hit.
3. The "Shared Meaning" Theory
Relationship psychologist John Gottman emphasizes the importance of creating Shared Meaning. Lasting couples are not just those who love each other, but those who build a "culture" together.
If there is no similarity and no shared reason (purpose), then:
- You live "parallel lives" (existing under the same roof but separately), not "shared lives."
- There are no shared rituals, shared dreams, or narratives of "us against the world."
- This lack of shared meaning creates an emotional emptiness that often leads to breakup due to loneliness within the relationship.
4. Social Exchange Theory
This theory views relationships as a "Cost vs. Benefit" calculation:
- Costs: Effort to understand a very different partner, conflicts from value differences, energy to tolerate mismatches.
- Benefits: Emotional support, security, happiness.
If there is no similarity (high communication costs) and no strong reason (low future benefits), humans will psychologically withdraw. Our brains are wired to seek efficiency; maintaining a relationship that is emotionally costly without a clear purpose is seen by our subconscious as a "foolish investment."
Conclusion
Psychologically, a relationship can end not because of a third party or a big fight, but because of the silent erosion caused by two things:
- Fatigue: Tired of constantly bridging too wide differences in principles.
- Lack of Purpose: Not knowing where the relationship ship is sailing.
A healthy relationship requires "enough similarity" to make communication smooth, and "enough reason" to make the struggle worthwhile.