Counterfactual emotions, such as regret and relief, are considered important in daily-life choice behaviour, learning and emotion regulation. A prominent question is from which age counterfactual emotions develop. In this study, we compared a more “traditional” analysis with a latent-class analysis (LCA) that allows the study of individual differences and a more detailed assessment of counterfactual emotions. Four groups of children (5–6 years, 7–8 years, 9–10 years and 11–13 years) and a group of young adults performed a choice task in which they encountered a Regret situation (chosen option was worse than alternative), a Relief situation (chosen option was better than alternative) and a Baseline situation (chosen option was equal to alternative). Traditional analyses indicated regret and relief to be present from ages 7 to 8. In contrast, the LCA indicated that subgroups experiencing regret and relief were present in all age groups, although regret and relief subgroups increased with age. Moreover, analyses indicated that higher reasoning scores increased the probability to belong to regret and relief subgroups and that the experience of regret dependent on trial order, being more prominent in later trials. We conclude that an individual-difference approach can advance insight into emotional development.