plunge into deep depression
The phrase 'in eine tiefe Depression stürzen' is used in German to express the idea of plunging or falling into a state of deep depression. This can be used metaphorically to describe a sudden, severe onset of depression or a rapid decline in mood.
After losing his job, he began to fall into a deep depression.
This sentence implies that the loss of the individual's job was a triggering event that led him to start spiralling into a deep depression.
The failure of his relationship made him fall into a deep depression.
This usage illustrates that the ending of his relationship was the direct cause for him falling into a deep depression.
The diagnosis made her unexpectedly fall into a deep depression.
In this context, the 'diagnosis' being referred to took the individual by surprise and led to a downward spiral into depression.