Desperately Need Help with Long-Distance Relationship!

Deanna
My boyfriend and I are absolutely perfect for eachother, and are so unbelievably happy when we are together. Having him in my life is honestly a dream come true! However, we are on opposite sides of the country and it is causing major problems. I am planning on moving to his area in about six months, but he isn't sure if he can last until then... 
 Personally, I was in a very bad relationship before him so the distance doesn't seem like a break-up worthy problem. I know it could be a lot worse, but as his first serious relationship, he is extremely unhappy with it. I am trying my best to stay strong for both of us, but it is really hard because I miss him too. He is getting to the point where he doesn't want to talk me because he gets more upset over missing me. 
He keeps saying that it is the situation making him so unhappy and not me, but I am the main factor in the situation. I just hate the thought of causing him pain! 
So far, we have tried: texting, the couple app, video chat, and talking on the phone. 
Any ideas of what else could help? Have you been in a long-distance relationship? If so, how did you make it work? 
Thank you in advance for your help!