The differences between verbal abuse and conflict which is a healthy part of a relationship can be very subtle. Most people will often try and justify their partners verbal abuse towards them. ie: It is because they are stressed out and maybe if I was different. These justifications help to perpetuate the cycle. One of the biggest justifications is that they will change their behaviour.
The reality is that you cannot change someone else but you can create change in yourself if you want to. That change might be having the strength to realise that she/he will always be verbally abusive but I am choosing not to stay in that relationship. These are very big and difficult changes to make which is why some people become trapped in abusive relationships.