Background: Previous research focused on relationship commitment as the outcome of high satisfaction, poor alternatives, and high investments. We propose that commitment is a prerequisite in highly satisfied couples, fostering relationship maintenance behavior such as positive dyadic coping. Method: Structural equation models identified the relationship between commitment, relationship satisfaction, and dyadic coping with data from 201 heterosexual couples with an average relationship length of 34 years. Results: The common fate model confirmed that relationship satisfaction mediated the effects between commitment and dyadic coping on a latent dyadic level. Additional analyses revealed that women’s satisfaction was mainly responsible for mediating effects between both partners’ commitment and dyadic coping. Conclusions: Findings support the essentiality of commitment for couples’ maintenance strategies and for consistency in long-term relationships.