Tom Tryon didn't like this movie!??
So I was reading the book Conversations With Writers and there's an interview in it from 1977 with Tom Tryon, conducted by Robert Dahlin. Turns out Tryon really hated what Robert Mulligan did with his book/screenplay:
"Oh, no. That broke my heart. Jesus. That was very sad... That picture was ruined in the cutting and the casting. The boys were good; Uta was good; the other parts, I think, were carelessly cast in some instances--not all, but in some instances. And, God knows, it was badly cut and faultily directed. Perhaps the whole thing was the rotten screenplay, I don't know. But I think it was a good screenplay.
"... "It was all step-by-step up to the point of whether I was going to become a director or not. The picture got done mainly because the director who did it wanted to do that property, and he was a known director; he was a known commodity."
Ouch.