Contrary to evolutionary psychology's emphasis on matching 'mate value' (e.g., a 7 with a 7), research shows that mismatched couples (e.g., an 8 with a 5 in attractiveness) are no more likely to break up, be unhappy, or cheat. The initial perceived value difference does not predict long-term relationship success.

To counteract the "suffocation model," couples can strengthen their bond by not relying on it for every need. Building a diversified "social portfolio"—turning to different friends, family, and hobbies for various forms of emotional support and fulfillment—reduces pressure on the marriage and improves overall happiness.

The key to a successful long-term relationship isn't just chemistry; it's a partner's psychological stability. This is measured by how quickly they return to their emotional baseline after a setback. This resilience is more predictive of success than more fleeting traits.

Contrary to popular belief, a degree of pessimism is a useful tool for building resilient relationships. Expecting a partner to be imperfect, frustrating, and disappointing at times creates a stronger foundation than entering a relationship with idealized, fragile expectations.

A common myth is that good relationships lack conflict. The reality is that the strength of a relationship is determined by its ability to manage and grow from conflict. The key metric is whether each argument makes the bond stronger (healing to 101%) or weaker (healing to 99%).

Evolutionarily, pair-bonding is crucial for survival. Yet, in conflict, the immediate gratification of "winning" often feels more compelling than maintaining connection. Recognizing this internal conflict—"you can be right or you can be happy"—is key to prioritizing the relationship's long-term health.

To maintain relationship stability, people in committed relationships unconsciously deploy a 'pro-relationship bias.' They automatically perceive attractive alternative partners as less appealing than they actually are. This psychological defense mechanism downgrades temptations and helps insulate the relationship from outside threats.

Viewing commitment as an 'obligation that restricts freedom' fosters fear and avoidance. Redefining it as a 'dedication to a cause'—the cause of your shared future—transforms it into a heroic, empowering act. This mental shift is crucial for investing in long-term partnership.

The success of a long-term relationship is better predicted by how partners handle conflict and disagreement than by how much they enjoy good times together. People are more likely to break up due to poor conflict resolution than a lack of peak experiences.