They tolerate small disappointments without making them stories

Their partner forgets to pick something up at the store. Cancels a plan because of unexpected work. Replies with something short on a day when a longer reply would have been nicer. Mature people have a wide tolerance band for the small frictions of two lives intersecting. They don't promote every ordinary humanness into evidence of a pattern, or every disappointment into a data point in a case they're building. The alternative — the tendency to archive minor disappointments and retrieve them during larger conflicts — is one of the most corrosive habits in long-term relationships. Every small frustration that gets turned into a story ('this is just how he always is') adds weight to a narrative that eventually becomes heavy enough to distort everything. Small disappointments are the weather of a shared life. They are supposed to pass. The ones that genuinely matter will make themselves known without the help of an archive.