This paper applies the clinical thinking of Wilfred Bion to the field of psychoanalytic couple therapy. A relationship may form a container for the container–contained dynamics of the couple, involving temporal and spatial aspects as well as an intersubjective relational third, an unconscious co-creation of the couple. Partners may bring to the new relationship their respective ‘malignant dowries’, consisting of unconscious unresolved traumatic material. The dowry box releases its nefarious contents to create an entangled interpersonal drama that I call the ‘interlocking traumatic scene’. The defensive systems that the two individuals bring dovetail together, and the interlocking mechanism may deadlock in such a way as to exert a ‘malignant third’ presence, militating against psychological growth and learning from experience. ‘The conjoint selected fact’ refers to how the selected facts pertaining to each partner cohere to create a third thing (after Bion, 1963; after Poincaré, 1952). It is related to a non-pathological use of Bion’s concept of reversible perspective. The process of intuiting a conjoint selected fact may also involve uncovering networks of links between four layers of history lying behind the present issue: the current relational situation, the couple’s marital history, internalisations of family-of-origin relational experiences, and intergenerational traumatic matters cross-transmitted in the current relationship.