(1) Background: Maladaptive daydreaming (MD) is a concept that describes a significant imaginary activity that replaces human engagement and/or interferes with academic, interpersonal, or vocational functioning. We explored the interaction between attachment style, reflective functioning (RF), and the narrative dimension of MD. (2) Methods: 414 adults completed an online survey, including socio-demographic variables, the 16-item Maladaptive Daydreaming Scale, the Symptom Checklist-90-Revised, Relationship Questionnaire, and Reflective Functioning Questionnaire. Participants were asked to write a short description of the most representative episodes of their daydreams. Eighty-four participants were identified as maladaptive daydreamers (MDers). (3) Results: A set of t-tests between MDers and non-MDers group showed differences in attachment dimensions, RF, and linguistic measures. A linear regression model with Global Severity Index (GSI) of the revised Symptom Checklist-90 as the dependent variable, and psychological scales as independent variables showed that the MD score was the strongest predictor of GSI. Regarding differences between the two groups in linguistic measures, the MDers showed more use of reflection and sensory-somatic words, and a smaller number of affective words. (4) Conclusions: These results support the idea that the MD is a process connected to psychopathological mechanisms, probably to a sub-symbolic activation, and to dysfunctional self–other relational patterns that are difficult to integrate.