A computer-implemented system measures loyalty of one partner to another partner in a relationship, such as the loyalty of a company's customer to the company. The first partner's loyalty is measured by obtaining information from the partner, such as through answers to survey questions, about the partner's perception of the climate of the relationship. A loyalty index function may be applied to scores associated with the answers to produce a single loyalty index representing the first partner's loyalty to the other partner. The system may recommend that the second partner change their practices to increase the first partner's loyalty index. For example, the system may recommend that the second partner improve practices related to “satisfier” dimensions of the relationship, and/or that the second partner improve practices which empirical data have demonstrated to correlate most strongly with increased loyalty.