Psychologists Explain Brain Processes That Make Ending Relationships Difficult

Psychologists say several brain-based processes make it harder to end long-term relationships even when a person wants to leave. These include sunk cost thinking, identity fusion, adult attachment patterns, and anticipated grief. Sian Khuman, a consultant psychologist and couples therapist, said people often weigh past investments of time, energy, and money more heavily than current circumstances.

Carly Dober, a psychologist and policy coordinator at the Australian Association of Psychologists, noted that individuals may tell themselves they have already given ten years and must continue, even when the relationship is no longer satisfying.

The longer a couple stays together, the more their lives and self-concepts become intertwined. Jeff Guenther, a mental health counsellor, said leaving a partner can feel like losing part of oneself. Khuman added that shared routines, friend groups, family connections, and future plans can make separation feel like losing everything.

Adult attachment formed in long-term relationships activates the same brain systems that seek safety and security. Khuman said the prospect of losing these supports can trigger fear of being alone or unprotected. Dober noted that research shows perceived rejection or anticipated loss can register as physical pain.

Khuman said the expected pain of a break-up is often greater than the actual experience. She recommended journaling, speaking with a trusted person, or consulting a therapist to test whether the fear matches reality. Dober said recognizing that the known can feel safer than the unknown helps people examine the barriers they face.

Khuman said the fear of leaving eventually passes as the brain adjusts to being out of the attachment. She added that people can still gain learning and growth from a relationship even if it ends.