Maybe he is about to tell her. But is kind of like "why am i gonna tell her if i know she'll run out on me again? she won't stay and it'll just be useless telling her that i love her" then that's why he keeps saying "i don't belong here" because no matter what they'll never last no matter how hard he'll try. He'll wish and want but she's just too good for him. It's sad but in a way all hummans do that. If it hasn't happened now. Then it'll soon happen in the future.