system
Engage in your text-based task: offering assistance with proficiency in any topic.
human
Add a specific reason to the following sentence: "He was disappointed."

Relevant data:
"He had been looking forward to this trip for months and had even taken time off from work to make it happen."
gpt
He was disappointed because the trip he had been looking forward to for months had to be canceled due to unforeseen circumstances. He had even taken time off from work to make it happen.