This study attempted to extend research on cognitive structure and affective extremity to help understand the dynamics of interpersonal relationships. Individual members of dating couple relationships (n = 51) described their partners in a card-sorting task used to assess cognitive complexity and completed measures of affect in their relationships. Contrary to earlier studies that had found a number of cognitive dimensions to play a large role in judgemental extremity, the redundancy of the dimensions (i.e. whether unique or the same attributes were used to describe different facets of the partner) was most important. Greater redundancy in a perceiver's cognitive representation of the partner was associated with greater perceived likelihood of remaining with the partner, and greater positive affect and less negative affect being felt toward the partner.