In relationships, some people may unintentionally or intentionally drain your energy, affect your well-being, or cause self-doubt. Psychological research has identified certain profiles that are often better avoided or limited. While it's not always necessary to end a relationship, some dynamics require constant adaptation, apology, or justification, which can lead to long-term psychological distress, anxiety, and depressive symptoms, as found in a 2009 study published in the National Library of Medicine. One type of person often linked to harmful relationships is those who are tactically manipulative. These individuals may display "dark" personality traits, such as narcissism, Machiavellianism, and psychopathy. Research from 2019 suggests these traits are associated with more manipulation and aggressiveness in relationships. Behaviors may include making vague promises that are later broken, shaming others when boundaries are set, or showing charm that quickly turns to coldness when it no longer benefits them. Another group is controllers, who take over aspects of your life, often under the guise of concern or love. A 2024 study on coercive control found these behaviors can have significant impacts on mental health, including depression and post-traumatic stress symptoms. Signs to watch for include surveillance, frequent questioning, systematic jealousy, isolating you from others, and pressuring you to make personal choices they prefer. Psychological aggressors engage in behaviors such as humiliation, belittlement, and teasing, often for what they consider "fun." A 2006 study found that victimization by psychological aggression is linked to increased psychological distress and anxiety, sometimes more than physical aggression. This type of harm is serious and should not be dismissed. Lastly, there are reality inverters—people who make you doubt your own experiences or perceptions. They may deny what you have seen, heard, or felt, using tactics of confusion and psychological domination. A 2024 study highlights these behaviors as tools of power with lasting effects on mental health. Examples include denying past statements, claiming you are too fragile, or suggesting others think you are complicated. Before deciding to end a relationship, consider how it makes you feel. If it consistently leaves you tense, guilty, or empty, setting a boundary or leaving may be the right choice.