Social support research suggests romantic partners could play a vital role in the success of individuals' weight management (WM) efforts, but contradictory findings from previous research have impeded our understanding of how romantic partners influence weight management goal attainment. Employing a confirmation perspective, overweight participants (body mass index [BMI] greater than 25) who were actively trying to manage their weight (N = 53) were asked to respond to daily questionnaires for a period of 2 weeks regarding their interactions with their romantic partner. Diet, exercise, and general weight management goal accomplishment were assessed. HLM was employed to assess the independent and interactive effects of partner acceptance and challenge on each of these goals. Findings suggest that perceiving high levels of both acceptance and challenge from partners was associated with more general WM and diet goal accomplishment. However, greater attainment of exercise goals was associated with only challenge. Fluctuations in partner acceptance and challenge were also examined to determine whether consistency in confirmation behaviors was associated with WM goals. Hierarchical regressions revealed that fluctuations in acceptance, but not challenge, were linked with goal attainment. Specifically, fluctuations in acceptance were helpful for those whose partners were perceived to exhibit lower levels of acceptance, but fluctuations were detrimental for those whose partners exhibited greater acceptance. Implications for communication among couples in which one partner is attempting to lose weight are discussed.