Domestic violence includes forms of physical abuse, such as physical and sexual assault, as well as emotional abuse, such as intimidation. Today, domestic violence is also often referred to as "intimate partner violence".
An intimate partner can be anyone with whom another person has a romantic/intimate relationship. Intimate partner or domestic violence occurs in both hetero and same-sex relationships.
The suggestion that someone in an abusive relationship simply needs to leave it can be quite harmful as the act of leaving can be very dangerous for them. Often, the reasons a victim of domestic violence does not leave are quite complicated.
The National Domestic Violence Hotline provides a comprehensive and informative list of common reasons--including fear, lack of self-esteem, and economic and religious reasons-- victims stay in abusive relationships
Gaslighting is a method abusers use to gain control over their victims. It involves using deceit, manipulation, and acts meant to cause confusion to convince their victims not to believe reality. The goal is to cause victims not to trust themselves in order to trap and control them.