The purpose of this study was to describe negative changes in parents’ relationships following the death of their child. A request to join the study was presented to members of grief associations through email and websites. Additionally, data were gathered through closed internet-groups where parents who had experienced the death of their child were logged in (e.g. in Facebook). The study participants were mothers (n = 321) and fathers (n = 36) whose child had died. The data were analysed using inductive qualitative content analysis. As negative changes in their relationship following the death of their child, parents reported the following: problems caused by failing mental health, problems due to changes in identity, increased difficulty of emotional communication, and decreased sexual intimacy. In addition, decreased sense of togetherness, behaviour that damages the relationship, everyday life straining the relationship, and emotions straining the relationship. It is concluded that a child’s death brings many kinds of negative changes to the parents’ relationship. The changes manifest as problems in the parents’ interaction, their behaviour, and their emotional life. The results can be utilized in supporting the relationships of grieving parents, developing different kinds of support interventions, and in nursing education.