Obsessive relational intrusions (ORI) are the repeated and unwanted attempts by one person to initiate or maintain an intimate relationship with a specific, targeted, and unwilling other. To date, ORI has been commonly explained by relational goal pursuit (RGP) theory. Centrally, RGP theory posits that five clusters of goal-related cognitions and emotions explain ORI. These are goal-linking, self-efficacy, rumination, affective flooding, and rationalization. However, while the first four factors have been empirically investigated as predictors of ORI, rationalization has not. Thus, the current study aimed to reintroduce rationalization to the evaluation of the RGP model among heterosexual former intimate partners. Participants (N = 379; 45.6% female, Mage = 34.4) were recruited from North America and completed an online survey assessing the RGP factors and engagement in ORI. Overall, we found that, after the other factors from the RGP model were considered, the inclusion of rationalization increased the variance explained in ORI. Furthermore, the rationalization subfactor of distortion (as opposed to permissiveness) uniquely predicted ORI both at a broad level and across specific clusters of ORI behavior. These findings not only support the inclusion of rationalization within the RGP model but also provide initial evidence that this construct might be the most individually critical to the explanation of a wide array of ORI behaviors. In addition to having implications for the prediction and explanation of ORI, these findings can also be used to direct clinical treatment of ORI perpetrators toward addressing defenses of rationalization.