Female coalitions are an important part of the social organization of bonobos. The strength of the mother-son relationship is another essential part of this social structure. A bonobo mother is therefore facing a dilemma when a conflict arises between her sons and her female coalition partners. Will she take her coalition partner’s side and favour the social organization of the group or support her son in order to defend her offspring? In order to address this issue, we performed an observational study of the captive group at Planckendael (Belgium) and used social grooming and proximity to assess the relationship between individuals. As a case study, we focused on the relationships between Hortense, one of the group’s mothers, her 3 sons Redi, Vifijo and Zamba, and her coalition partner Hermien. Surprisingly, we observed that Hortense preferentially supported her female coalition partner. For Hortense’s social status in the group, it may be more important to maintain the strong relationship with her higher-ranking female coalition partner than to support her sons.