Feeling loved by one's caregiver is essential for individual flourishing (i.e., high levels of psychological well-being in multiple dimensions). Although similar constructs are found to benefit adolescent well-being, research that directly tests parental love as a feeling from the recipient's perspective is rare. Historically, parental love has been measured using single-assessment methods and assumed to be a stable, trait-like characteristic; yet, like any feeling, it may fluctuate in meaningful ways on a day-to-day basis--the implications of which are unknown. Using a sample of 150 adolescents (59.3% female; ages 14-16), this study estimated "level" (person's mean level across days) and "instability" (fluctuations across days) of feeling loved by a caregiver across 21 days for each adolescent, and then examined their prospective effects on adolescent flourishing 1 year later. After controlling for demographics (adolescent age, gender, family income, and parent's sex) and variable baseline levels, feeling more loved by one's caregiver in daily life significantly predicted higher levels of flourishing in two global measures 1 year later. Moreover, "level" and "instability" of feeling loved by one's caregiver played different roles for different dimensions of flourishing: higher "levels" significantly predicted higher levels of autonomy, purpose in life, and personal growth, whereas higher "instability" significantly predicted lower levels of positive relations with others and environmental mastery. Findings emphasized the importance of considering daily dynamics of feeling loved by one's caregiver and demonstrated that "level" (of feeling loved) is particularly important for intrapersonal aspects while "instability" is particularly important for interpersonal aspects of flourishing.