Supportive communicative experiences within close relationships, such as dyadic support, have a protective effect on individuals' health and emotional well-being. However, little is known about how partners interact in determining their own and others' health or the mechanisms through which dyadic support influences physical health. We addressed those gaps by studying 1088 romantic couples from three consecutive years (T1, T2, T3; Swiss Household Panel). The study applied a data analysis strategy called Actor Partner Interdependence Model extended Mediation, which allows for mediation processes while considering the interdependence, or non-independence, of data coming from partners. Results showed that dyadic support was positively associated with perceived health over two years through the mediation of optimistic attitudes and depressive mood, both for person and partner effects. The present study demonstrates the interplay between the dyadic process and personality dispositions in maintaining good health.