I think It's about there being no chance for him to continue his life happily, and following his dreams. Once in a while you have to say goodbye to the ones you love. Including your parents. I understand how some people think this song might be about suicide. But like Fl8 said, most of these things he is saying point to a hypothetical suicide, not an actual one. Basically, he has to leave. He needed his parents to accept the fact that he needed to follow his dreams. And they couldn't do that so he left. "Sometimes goodbye is a second chance."