This study comprehensively addresses the clinical phenomenon of Partner/Spouse Alienation Syndrome (PSS), where an individual in a romantic relationship or marriage experiences a systematically negative transformation in their feelings, thoughts, and values ​​towards their partner or spouse, without any objective change. The study includes the philosophical and sociological origins of the concept (etymology), the stages of syndrome development, the differing factors and symptom patterns in the context of romantic relationships and marriage, the points where it differs from existing psychological concepts, and a multi-stage treatment plan based on current theoretical frameworks, primarily Acceptance and Commitment Therapy (ACT), Cognitive Behavioral Therapy (CBT), and Narrative Therapy. Each chapter is supported by clinical case studies.