I'm not going to speculate on his reasons. I will only add this. As a person who played 5 years of college football I have seen many of people quit for many reasons. Admittedly none of them had the timing of this. However I had the luxury of never playing on a team with a losing record.
My main point is these types of things are very unpredictable.
I've had teammates quit for the following reasons.
Missed deer hunting too much
Landed a killer internship in Washington DC on capital hill
Got a girl knocked up
Missed their girlfriend
Was failing all classes
Wanted to focus on maintaining high GPA
Decided to play basketball at a different school
Wanted to party more
Missed milking cows too much (seriously)
Been there.
Point is he felt his reason was worth leaving and focusing on the next stage of his life. I am concerned about the direction of things but just wanted to point out that his reasons could also have nothing to do with the program.