REBT encourages acceptance. Acceptance is the antidote for emotional upset. Acceptance does not mean liking what has occurred or resignation. Acceptance means acknowledging that a negative state of affairs has taken place and for the time it exists one is able to emotionally tolerate its existence and live on somewhat happily despite its existence. This emotional and philosophical tolerance is associated with a strong preference that the negative states of affairs not exist.
Due to human fallibility people will often resisting accepting things which they think absolutely should not exist. My response to this resistance is that one is free to reject acceptance but one does so at their own emotional peril. When you reject acceptance you think a particular state of affairs absolutely should not exist and you experience emotional distress. This is the personal cost of a lack of acceptance. The art of therapy is helping people achieve a state of acceptance until something can be done to wisely change the negative state of affairs.
Acceptance is not an easy thing to achieve for fallible humans. It is our nature to resist accepting things we do not like. Acceptance is rarely quickly achieved in matters that are close to the heart. Nevertheless, it is the only leverage we have over a negative state of affairs while that state of affairs continues to exist. Once you come to appreciate this you are liberated from the emotional upset that is tied to a lack of acceptance.