Borderline Personality Disorder (BPD): Characterized by a lifelong pattern of unstable relationships, emotional dysregulation, and impulsivity. The patient's history of chaotic relationships and poor impulse control aligns closely with the diagnostic criteria for BPD.

Histrionic Personality Disorder: Marked by excessive emotionality, attention-seeking behavior, and inappropriate seductive behavior. While the primary symptoms don't perfectly match, some overlap with BPD and the presence of chaotic relationships could suggest this diagnosis.
Antisocial Personality Disorder: Characterized by a disregard for others' rights, lack of empathy, and impulsivity. The mention of poor impulse control and chaotic relationships could be indicative of this disorder, although a lack of empathy and disregard for others' rights are key distinguishing features.
Narcissistic Personality Disorder: Involves a grandiose sense of self-importance, a need for admiration, and a lack of empathy. While less directly related to the symptoms described, narcissistic traits can sometimes manifest as chaotic relationships due to an inability to empathize with others.

Trauma- and Stressor-Related Disorders (e.g., Post-Traumatic Stress Disorder - PTSD): Given the patient's history of chaotic relationships, it's crucial to consider the possibility of underlying trauma. PTSD or other trauma-related disorders could explain some of the patient's behaviors and should not be overlooked due to their potential impact on treatment and prognosis.
Substance Use Disorders: Substance abuse can significantly impact impulse control and relationship stability. It's essential to assess for substance use, as it could be a contributing factor to the patient's symptoms.
Neurocognitive Disorders (e.g., Frontotemporal Dementia): In a 71-year-old patient, it's critical to rule out neurocognitive disorders that could affect impulse control and social behavior. Frontotemporal dementia, for example, can lead to significant changes in personality and social conduct.

Intermittent Explosive Disorder: Characterized by recurrent, problematic, impulsive aggression. While this could explain some of the impulsivity, it's less likely to account for the full spectrum of chaotic relationships and interpersonal conflict described.
Factitious Disorder: Involves the intentional production or feigning of physical or psychological symptoms. This is a less likely diagnosis but should be considered if there's suspicion that the patient is fabricating or exaggerating symptoms for attention or other gains.