Why Can't He tell?

After reading the chapter "Speaking of Courage" and a few of the chapters following that, I am still a little confused on why Norman Bowker just couldn't tell anyone about what happened that night on the shit field in Vietnam. He goes throughout the whole chapter imagining what his dad would say to his story or how a girl would react to his story. The dialogue would go like this: " 'Well anyway,' the old man would've said, 'there's still the seven medals.' " But why can't he tell them? He as that story bottled up inside of him for so long, and it probably is something that contributed to his suicide. If there is a deeper meaning in this story about Bowker than I don't understand it. I know he gives a reason to why he doesn't tell the different people. There has to be someone, however, that he would be able to tell.