Emotions, like regret, have been heralded as instruments of self-regulation, by instigating reflection, learning and feedback for betterment and thus increasing well-being. Yet, this view neglects taking the frequency of regret into consideration. Frequently experiencing regret may instead be a sign of repeatedly failing to achieve betterment. Previous work has shown that people who experience regret often have lower life satisfaction. We suggest that, by itself, the reflective function of regret is not enough to lead to betterment. Rather, in addition to regret, self-regulatory abilities are needed. In the absence of these abilities, the reflective function of regret does not turn off but is likely to lead to frequent episodes of regret and turn into counter-productive rumination, reducing rather than increasing well-being. We tested these possibilities in two studies. In Study 1, reports were administered about regret frequency, self-regulatory abilities, and life satisfaction in 388 US adults (54.6% males; Mage = 35, SD = 10). In the preregistered Study 2, the same instruments were administered in a replication sample of 470 British adults (22.1% males; Mage = 36, SD = 12). In both studies, low self-regulatory abilities were associated with higher regret frequency, which in turn, was associated with poorer life satisfaction. Moreover, in both studies, the negative association between regret frequency and life satisfaction was explained by ruminative brooding styles. In sum, the positive reflective function of regret for well-being cannot stand alone, but needs self-regulatory abilities. Without these abilities, regret experience is frequent and its reflective function turns into brooding rumination that negatively affects well-being.