The aims of this study are (1) to identify sources of uncertainty breast cancer survivors and partners of breast cancer survivors (BCS) report as a result of sexual health changes after primary treatment and (2) to investigate the challenges they experience when attempting to communicate about sexual health-related uncertainty. Forty BCS and 13 partners completed written reflections and participated in semi-structured interviews. Analyses revealed five predominant sources of uncertainty for BCS and partners: perceptions of post-treatment body, worry about effects on relational partners, ethical concerns about dissatisfaction with sexual relationship (partners only), fears about future of the relationship, and apprehension about SH treatment futility. These concerns are linked to communication challenges for couples: supporting survivors' body esteem, navigating potentially hurtful disclosures, responding to partners' "obstructive behavior," and believing communication is futile. Findings suggest women and partners find themselves caught in a destructive cycle that reinforces uncertainty and inadvertently perpetuates silence and relational distress. To disrupt the cycle of silence, BCS and partners need to know that their interpretation of the other person's behaviors/needs is not always accurate. Strategies are required to help women and their partners express uncomfortable thoughts and feelings in safe and supportive environments. Practitioners should be conscious of potential SH issues, be familiar with existing support resources for survivors, and be prepared to disseminate information that will empower women and their partners.