Background Withdrawing effort and commitment from important goals (i.e. goal disengagement) has been discussed as an effective aspect of goal adaption. However, studies have focused especially on between‐person differences. The present studies aimed to investigate within‐person differences in goal disengagement within a dyadic context of romantic couples. Across two different health behaviors, we specifically tested whether goal disengagement would be associated with better well‐being, but lower goal achievement in everyday life. Methods In two dyadic daily diary studies (Study 1: 61 overweight couples aiming to become physically active; Study 2: 83 dual‐smoker couples aiming to quit smoking), both partners independently reported on goal disengagement, positive and negative affect. Behavioral goal achievement was measured via accelerometer (Study 1) and self‐report (Study 2). Results Analyses based on the Actor‐Partner Interdependence Model revealed that across both studies, one's own goal disengagement was related to lower well‐being and a lower likelihood for goal achievement on a daily level (actor effects). Only in Study 1 were partner effects on negative affect and goal achievement found. Conclusions In daily life, goal disengagement may not be as adaptive for well‐being and goal achievement in health behavior change. Dyadic associations were not consistent, and might be more context‐sensitive.