why do people abuse?

Domestic violence and abuse stem from a desire to gain and maintain power and control over an intimate partner. Abusive people believe they have the right to control and restrict their partners, and they may enjoy the feeling that exerting power gives them. They often believe that their own feelings and needs should be the priority in their relationships, so they use abusive tactics to dismantle equality and make their partners feel less valuable and deserving of respect in the relationship.  

No matter why it happens, abuse is not okay and it’s never justified.  
Abuse is a learned behavior. Sometimes people see it in their own families. Other times they learn it from friends or popular culture. However, abuse is a choice, and it’s not one that anyone has to make. Many people who experience or witness abuse growing up decide not to use those negative and hurtful ways of behaving in their own relationships. While outside forces such as drug or alcohol addiction can sometimes escalate abuse, it’s most important to recognize that these issues do not cause abuse.