Truth be told, people like the abusive person in this video may truly love their partners and are nonetheless abusing them and themselves by doing something for which the partners may need to take the hard step of leaving them: refusing to get treatment for mental illnesses if they can get that treatment.
In the video, the abusive person has Alcoholism for which he is clearly not getting treatment, although he can treatment for Alcoholism. Other mental illnesses which unfortunately can effect people to abuse other people include Bipolar Disorder and Schizophrenia: when people are in the throes of untreated mental illnesses like that, they're not even aware of what they're doing. According to the Mayo Clinic re Bipolar Disorder alone, "Despite the mood extremes, people with bipolar disorder often don't recognize how much their emotional instability disrupts their lives and the lives of their loved ones and don't get the treatment they need.".
Sometimes, then, the abused partners have to leave and say to their abusive partners something like, "I will come back if you seek the mental-health treatment that you need, and I will be fully supportive of you as you undergo the mental-health treatment. I cannot continue to let you hurt me and, ultimately, hurt yourself, and the only way that you can begin to heal yourself and mend the ties that you have cut is to acknowledge that you have a mental illness and get help for yourself."