Stress can be very insidious. I know from personal experience that one can be extremely stressed by events without feeling stressed or showing any outward signs of it. Then an event occurs that, on top of everything else, causes the individual to run out of “stress capacity” and their performance suddenly drops dramatically. They are not mentally ill, just overloaded.
It seems odd for a modern trainee pilot to be stressed by current airline flying or training to the extent that they leave the cockpit during landing (!), so maybe a career change is required. Having said that, who knows what other events were happening in their life? Possibly relocation, maybe first time living away from home, first time finding somewhere to live, difficult training course or nowhere quiet to study, not able to sleep fully, applying for airside security passes etc, etc, can be a heavy stress load.
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