The Fragility of AI Companionship: Ontological, Structural, and Normative Uncertainty in Human-AI Relationships

As generative AI chatbots become more personalized and emotionally responsive, they increasingly serve as companions, friends, and romantic partners. Yet these relationships are accompanied by significant uncertainty regarding AI's sentience, authenticity, and relational stability. Drawing on in-depth interviews with 25 users of AI companions, this study identifies three key forms of uncertainty in human-AI relationships: ontological uncertainty concerning the AI's nature and agency, structural uncertainty arising from platform control and system instability, and normative uncertainty regarding the legitimacy and boundaries of human-AI intimacy. Participants managed these uncertainties through information seeking, topic avoidance, expectation adjustment, and disengagement. This study extends interpersonal uncertainty theories to human-AI communication and contributes to HCI research by conceptualizing uncertainty as a socio-technical and relational phenomenon with socio-emotional implications. We discuss implications for designing safer AI companionship through contextual transparency, user control, update notice, and relational safeguards.