As is pointed out, the context of the poem "Daddy" is that of Plath's husband's affair with another woman. Grieved to the point of psychotic anger Plath's use of imagery throughout the piece accentuates the hopeless despair of the speaker at the conflicting male relationships in Plath's life: first her father and then husband.
"Any more, black shoe
In which I have lived like a foot..."
The metaphor of 'black shoe' possibly used to denote a person, suggests a stifling image. The speaker claims to have lived in that shoe, almost as if unwillingly trapped. While it suggests a sort of protection, the colour imagery of black, which is a recurring motif in the poem, connotes to negativity: death, even decaying. This could further be interpreted to suggest that Plaths own voice is accusing her father of having trapped her by his sudden death; she is almost disclosing her great weakness before him even after his death and again returns to the initial idea of conflict and confusion. It has been argued that Plath in making a feministic stance accusing the male domination in her relationship with her father and unable to break it she is psychologically shaken.