The study aimed to examine the effect of external stressors on the intimate relationship of parents of children with developmental disabilities and whether the influence of external stressors both chronic and acute leads to the "stress spillover" phenomenon manifested in reduced positive interactions, increased negative interactions and ultimately reduced satisfaction with the intimate relationship. In addition to external stressors such as work, social contacts, leisure and finances. The impact of parental stress on the intimate relationship of parents of children with developmental disabilities was separately investigated. The survey included 248 respondents across the Republic of Croatia who have been in an intimate relationship for at least 6 months and who live in the same household. The results of the research confirm the appearance of the "stress spillover" phenomenon. In addition to the confirmed association of external stress with decreased satisfaction within the partnership relationship, the association with less positive interactions under the influence of external stress was also confirmed, namely the association with more negative interactions within the intimate relationship of parents of children with developmental disabilities. The results state that the same can be applied to parental stress and its impact on interactions between partners. The research points out the need to conduct similar research and generally refocus attention on parents and their relationships, to provide them with adequate support and improve the quality of life, both to themselves and their children.