A relationship can score extremely high on chemistry and still fail the only test that determines its longevity; that test happens later, under different conditions, and chemistry was never built to pass it. Why This Trait Outweighs Attraction Over TimeThe reason this trait outperforms chemistry as a long-term predictor is arithmetic rather than romantic. Chemistry does not influence that outcome; by the time the provoking moment arrives, whatever chemistry contributed has already been spent. The relationship between self-control and good partnership is not perfectly linear, and the research is careful about this. The trait that predicts whether two people stay together in 20 years operates in a moment attraction doesn’t reach.