It sounds like she needs to read this. It sounds like she has high highs and low lows.

"In Buddhist philosophy it is considered impossible to maintain a state of "happiness" because a happy event is invariably followed by a sad one and vice versa. In fact the very nature of "happiness" and "sadness" is that one cannot exist without the other. It is the contrast that defines their existence. However, beyond happiness and sadness there is peace. This is not an emotion but a state of being. It has no opposite. When we experience peace, happiness and sadness are simply observed as transient emotions. They are defined by their impermanence. A beautiful metaphor for this is that our true state can be compared to a mountain. We are peaceful and grounded. Our emotions are like the weather and the seasons. Storms may pass, the mountain may be covered in snow or bathed in brilliant sunlight but all these things eventually will pass. In the end the mountain is just the mountain - the stillness underneath the storm."

https://www.katedelaney.co.uk/journal/2018/7/19/and-this-too-shall-pass