Distress and discord within couples lead to several impairments, including physical and psychological deterioration, and dramatically reduce life satisfaction levels. This chapter raises the following question: Is it possible to maintain and improve a dyadic bond, individual well-being and life satisfaction through a specific intervention? Although much literature has already addressed this issue via positive psychology interventions (PPIs) at the individual level, the involvement of couple dynamics is understudied. This chapter addresses the theoretical background and practical details of the implementation of a four-week theory-driven preventive self-help dyadic PPI called Couple+, which was adapted for heterosexual couples living in France. A preliminary study was conducted to assess the innovative multicomponent Couple+ intervention, which encompassed daily activities designed for the members of the dyad. The aim of Couple+ was to encourage romantic relationship development and maintenance by improving the couple’s functioning. The effect of this intervention was measured and compared with a control group on a waiting list. The preliminary results showed significant improvements in positive emotions, communication patterns, and dyadic adjustment. Considering Couple+ as a success in terms of feasibility and implementation, as well as both dyadic and individual outcomes, this study appears to be the first step toward the development of self-help positive psychology activities dedicated to improving the lives of couples.