Throughout a marriage couples will share countless ordinary moments together that may seem trivial, but which actually have potential to affirm and strengthen relational bonds. According to theories of emotional capital, the accumulation of shared positive moments in a relationship should serve as an essential resource for protecting the relationship against threats. To date, however, few empirical studies have explored the role emotional capital may play in shaping responses to negative relationship experiences. In the current study, newly married couples completed 3 14-day daily diary tasks assessing emotional capital, negative partner behaviors, and marital satisfaction over a 3-year period, for a total of 42 potential days of diary data. Contrary to predictions, emotional capital on a given day was not associated with reactivity to relationship threats on the following day. However, conceptually replicating prior work, individuals who accumulated more emotional capital on average across the diary tasks did exhibit lower reactivity to daily relationship threats; that is, on days of greater relationship threat (i.e., negative partner behaviors), those spouses who generally accrued more shared positive moments with their partner maintained greater feelings of marital satisfaction compared with spouses who accrued fewer positive moments. These findings contribute to a growing literature illustrating how positive shared activities between partners help sustain relationship quality over time.