REBT encourages you to spend MORE time changing YOU and less time attempting to change other people. It is easier to change you than it is to change others. Strive to accept people "As Is" and only put down what they do rather than putting them down as people for doing what they do. This idea is consistent with the idea of "Condemning the sin and not the sinner." If you only criticize what people do it will be easier to get along with them. If you criticize and condemn the person for their misbehavior you will be more prone to rage and unhealthy anger at the person.
So REBT is not advocating that you overlook misbehavior. It is advocating a practical stance towards it. People tend to do what they want and not what you want. This is the grim reality. You can choose not to upset yourself about this. You can assert your preference and you then can condemn what the person has done but accept the person as a fallible human who does good, neutral and bad deeds over the course of their lifetime. You can ask the person to respect your wishes and try to meet you half way towards your goals so that you and they live in harmony. This is a pretty sound and practical approach to living with fallible humans. Of course if people do not do what you want too much of the time you can choose not to relate to them. However, do not make this choice too quickly! Keep in mind if you leave one relationship and enter another one there is no guarantee that you won't encounter misbehavior all over again! This is why it is best to start to work on learning how not to upset yourself about the other person's misbehavior. In all human relationships there will be misbehavior of one sort or another. By learning to control your emotions you will be able to live better with the fallible human you choose to live with in the end.