A person with BPD may use splitting in the following ways:

• People will be seen as ‘perfect’ or ‘evil’

• Something will ‘always’ or ‘never’ go right

• Someone will ‘always’ or ‘never’ be loving

A person may hold onto these black and white views permanently. For others, their opposing views can fluctuate over time, where they switch from seeing someone or something as entirely good to entirely bad, or vice versa.

A common symptom of BPD is emotional dysregulation – this is where a person is less able to manage their emotional responses than people who don’t struggle with a personality disorder. Therefore, when a person with the disorder splits and perceives something or someone to be entirely good or bad, they're likely to respond in a way that falls outside what would be expected. These extreme emotions can be exhausting, both to the person with BPD and those who are closest to them.

When a real or perceived slight is then experienced by the person with BPD, this can cause them to feel disappointed, betrayed, unloved or abandoned, and view the other party as entirely bad. The person may then become angry, or withdraw entirely. They may also become incredibly angry with themselves.

During this exhausting process they may abruptly lash out or sever contact with those they once idealized, causing a great deal of conflict and distress. The severity of the split correlates more with the emotional weight in the person or event, rather than the triggering incident, which is often trivial. The more they loved or idealized someone, the worse they perceive them after the split.

People with BPD possess a high degree of self-awareness, and whilst splitting is subconscious it still often leads to feelings of shame and guilt. These feelings are often suppressed by reinforcing negative perceptions of the devalued individual. To prevent perceived judgment from others and protect their poor sense of self, individuals may justify their actions by convincing others of the validity of their claims that the devalued party is entirely bad, positioning themselves as victims.

Proneness to rejection hypersensitivity; problems in establishing and maintaining consistent and appropriate levels of trust in interpersonal relationships and frequent misinterpretation of social signals contribute greatly to a person with BPD's ability to find supporting "evidence" for their devaluation process.

Stress-induced paranoia, another recognised diagnostic feature of BPD, can exacerbate these tendencies during personal stress. In some cases, individuals may embellish or invent grievances to elicit an emotional response from friends or family that matches their own distress. The more valuable the social bond or the greater their need for social acceptance, the higher the likelihood of engaging in psychologically abusive behaviour. This can cause intense psychological distress in the person being devalued.

Many in relationships with individuals who struggle with splitting have stated that they feel as though they ‘tiptoe’ through their relationship because there is a constant sense of duty and worrying that their partner will split and begin to see them as the ‘bad guy’. Individuals have expressed the need to consistently validate and make sure their partner is understood due to their struggles with interpersonal identity and lack of self-worth.