Fragmentation: 

Fragmentation, as described by Melanie Klein’s object relations theory, is the primitive, dissociated splitting of the internal representations of self and others (objects) into many small, unintegrated, and often contradictory pieces—rather than a cohesive whole. The infant develops a fragmented sense of self when its relationship with the primary caregivers is disrupted (due to chronic stress, trauma, abuse, or neglect). It causes difficulty integrating the good/bad aspects of self and others into a complex whole, leading to poor self-identity and unstable relationships. Fragmentation is a core defensive mechanism in narcissistic personality disorder (NPD) andborderline personality disorder (BPD). It shows up as:

• Identity diffusion: Unstable and fragmented sense of self, struggling to form a cohesive identity. 
• Splitting of others: Inability to reconcile good/bad aspects of another person, oscillating between idealizing someone and devaluing them entirely (common in NPD). 
• Internal conflict: Simultaneously experiencing contradictory thoughts, feelings, or actions without a sense of a unified self to hold them together. 
• Relational instability: Tendency to oscillate between clinging dependency and defensive detachment in relationships.