This document discusses why seemingly satisfied customers may defect from a business. It notes that there is a gulf between customers who are satisfied and those who are completely satisfied, and relying solely on customer satisfaction surveys can underestimate dissatisfaction levels. The relationship between satisfaction and loyalty is explored, with satisfied customers more easily switching to competitors. Different types of customers are identified based on their satisfaction and loyalty levels. To secure customer loyalty, the document recommends clearly defining target customers, systematically measuring satisfaction through various methods, using satisfaction data to measure loyalty, and aiming to completely satisfy customers.