The present research examined how rumination influences implicit affect regulation in response to romantic relationship threat. In three studies, the disposition to ruminate impaired the ability to maintain positive feelings about the romantic partner in the face of explicit or implicit reminders of relationship threatening events. In Study 1, a high disposition to ruminate was correlated with impaired down-regulation of negative feelings toward the partner in response to a hurtful relationship incident. Two follow-up studies manipulated relationship threat explicitly through an experiential recall procedure (Study 2) or implicitly through a subliminal evaluative-conditioning procedure (Study 3). In both studies only individuals with low disposition to ruminate were able to ward off negative feelings and maintain positive feelings toward the partner. These findings illuminate the role of implicit affect regulation in the context of relationship threat*and how it is inextricably connected with the processes underlying rumination. © 2011 Psychology Press.