The cycle of high ups and deep downs in a relationship is like being trapped in an emotional prison. There are moments of freedom and happiness, followed by a constant underlying fear or worry of being trapped again.
The emotional prison is created by the manipulative and controlling behavior of the person who wants to keep the person in a disempowered state. This cycle of ups and downs often forms a trauma bond, where the person seeks love and support from the same person who is causing them emotional harm.