Relationships between two people can be stressful, but that is no reason for either partner to become abusive. It does happen, and the history of the couple will help them decide whether or not to end their relationship. If there has never been abuse in the past, they might be able to find a way to continue together. People who have a history of abuse or parents who were abusive are often not those who will be able to change their behavior when tensions overcome them.
Few people really want to end a relationship if they believe it can be salvaged, but giving a partner another chance is emotionally risky. The person who was abused has already been hurt, and they might feel they are being taken advantage of by a person who has little or no feelings for them. There are times when a partner loses control, so it could be good to give them another chance. If they have lost control several times before, it becomes more complicated.
There are people who lose control often, and they might be unwilling to admit they have a problem. For their partner, the loss of control can be both physically and emotionally damaging. They might continue to ask for another chance, but they will be limited unless they are willing to seek help with their own issues. If they are not willing to do something about the problem, their partner has a legitimate right to leave them.
Life is difficult for many reasons, but abusing a partner is never the answer. Giving a partner another chance after an unexpected loss of control is one thing, but more than one chance to change is something else. People who refuse to make necessary changes to their behavior do not deserve another chance at keeping their relationship, and it is best to make the break clean and fast.