Why can't he tell me if he wants/does not want to date me?

Long story short - we met 1.5 years ago online, we have traveled long distance to see each other every 4 months. he lives in australia and i am in texas (i have flight benefits so its much cheaper to see each other). we have talked all day every day since we met, always kiss/cuddle/be intimate when we are together in person, share our daily lives and what goes on always, and etc. we don't date other people and he has said he loves me even if he does express his emotions often or even if i don't think he does and absolutely never wants to stop talking... but.... when i ask if he wants to be official with me at some point he just says "i don't want to talk about this" or ignores it! i am so frustrated by this - i want a yes or no answer and he cannot give that. WHY in the world can he not just answer this question? i know there is distance, but i told him i would be open to moving over there and in time he could get a visa here. he is 25, i am 23. i know its far... but surely a man knows in his heart is he wants something or not? i just dont want to wait for nothing. please make sense of this to me!