A toxic relationship is one that diminishes your sense of well-being and leaves you feeling undermined, threatened, or unsafe. Perhaps your partner’s constant insults or controlling behavior make you feel disrespected and worthless. Or maybe they hold grudges and pick fights in ways that leave you feeling constantly stressed or on edge. It’s also possible for a relationship to become so demanding and codependent that you begin to neglect your own self-care. A toxic relationship can lead to social isolation, depression, and an overall decline in your mental health.