Parents form the central living space for children, especially in their younger ages. They are the primary caregivers - they are responsible and influential for a child's development. Therefore, it is crucial that parenting behavior is conducive to the child's development. Studies consistently show that children's psychological and physical health can be severely affected by parental conflict and disharmony (Harold & Sellers, 2018). The present study not only focuses on the relation between relationship satisfaction and the child's problem behavior (i.e., emotional problems, behavioral problems, hyperactivity, and peer problems), but also investigates the mediating or moderating role of positive parental behavior (i.e., involvement, positive parenting), negative parental behavior (e.g., physical punishment, inconsistent parenting behavior, powerful enforcement) and parental stress. Here, two hypotheses are contrasted: the spillover hypothesis versus compensatory hypothesis. The assumption under the spillover hypothesis is that an unsatisfactory partnership leads to negative educational behavior, which then has a negative effect on the development of the child (mediation hypothesis). This contrasts with the examination of the compensatory hypothesis, in which a favorable parenting behavior should buffer the negative relationship between partnership satisfaction and child problem behavior (moderation hypothesis). As part of the CORE (2) project (Conditions of Regulation and Coping Resources) 81 parents whose children were between 3 and 6 years old (M = 5.22 years, SD = 0.86) were cross-sectionally interviewed by pre-established questionnaires. Overall, the results suggest that the negative relation between relationship satisfaction and the child's problem behavior is completely mediated through negative parental behavior and parental stress. This confirms the acceptance of the spillover hypothesis. No moderating effects were detected, leading to a rejection of the compensatory hypothesis. In addition, negative parental behavior correlated significantly with problem behavior, while positive parental behavior did not significantly correlate with problem behavior of children. Although causal relationships cannot be deduced based on the cross-sectional design, it could be tentatively assumed that negative parental behavior plays a greater role in negative child behavior than does positive parental behavior in preventing it. The clarification of causality should be the subject of further investigations. The perception, reflection, and treatment of family dynamics, in addition to the treatment of children's behavioral problems, are crucial to ensure the best possible development for children.