Why did he end it after getting closer. And what am I going to do about our US trip?

Let him be, it hurts but demanding answers and pushing at him is forcing him away. If you want him back tell him you love him and can see he is in turmoil. Tell him you want him to be happy and your friendship is very important to you. That you will now respect his wishes and hope he can give you the same respect in return when he is ready and either give you some answers and ideally come back in friendship and hopefully love.