I can't say I know how to do that, either... but it's like you said. There must be a way to learn how to travel to the world she is from!
[He absolutely believes in that.] And besides... I heard that people sometimes leave and then come back here? Maybe she won't be gone forever. As long as you keep believing, and keep her dream alive... nothing is impossible. [He may not know what that dream is, exactly, but he knows everyone has a dream. And as long as someone continues it for you, when you can't-- it's still alive. It's still a part of you, there with them.]