Case. A marriage of 8–10 years: the routine works, few conflicts, but both feel they’ve become “roommates”.
Model. The system works, but nobody did maintenance — warmth degraded unnoticed, with no visible incident.
What helped. They brought back rituals of connection, novelty and “how are we” talks; treated the relationship as something needing regular care.
Lesson. No fights isn’t the same as closeness. Warmth needs maintenance.
See Emotional bank.