It was in the vortex of the student's revolution in the 1970's. One day, when he come home dead tired after taking part in the demonstration, the lover prepared dinner. At that time, he thought like "Maybe...I should acquire certificate in teaching rather than taking part in the demonstration. If I do, we could be happy in the future". He wavered in his belief of revolution in Japan because of the lover's 優しさ. That's why 貴方の優しさが恐かった.
I'm sorry for my poor English, make sense?