BackgroundPsychological maltreatment may be one of the causes of adults' loneliness despite having a partner. There are some links between psychological maltreatment, self-criticism, relationship satisfaction, and loneliness in the literature. But the nature of these links requires further explanation. ObjectiveThe present study examined the serial mediation role of self-criticism and romantic relationship satisfaction on the pathway from childhood psychological maltreatment to loneliness, in a Turkish sample. Participants and settingsIn total 403 individuals (Female = 294, Male = 109) participated from 53 different cities in Türkiye. Participants were either dating (65.8 %), had a fiancée (4 %), or were married (30.3 %). MethodThe data was collected using Psychological Maltreatment Questionnaire, UCLA Loneliness Scale, Self-criticism Rumination Scale, and the Relationship Assessment Scale. ResultsStructural equation modeling results indicated that self-criticism and romantic relationship satisfaction fully mediated the impact of psychological maltreatment on loneliness. The model was a good fit [χ2 (29, N = 403) = 63.846, p < .001; χ2/df = 2.20; SRMR = 0.061; RMSEA = 0.055; GFI = 0.969; CFI = 0.979; NFI = 0.963; IFI = 0.979]. ConclusionsChildhood experiences of psychological maltreatment can continue to haunt individuals, even as adults. Although being in a relationship can help individuals with their loneliness, psychologically maltreated adults may feel lonely in their relationships due to self-criticism and dissatisfaction. Interventions focused on childhood psychological maltreatment and self-criticism may help lonely adults. Along with this focus, relationship satisfaction can be addressed in family/couple counseling.