Give the poor man some space. If he needs some quiet for a bit, then you would be wise to respect that. The point is to talk your problems through eventually. One way to find out if he is ready to talk is to sit down next to him with your thigh touching his, and you might also put your hand on his thigh. If he doesn't move away, ask him, "Are you ready to talk? (Say this nicely) If he nods yes, then try not to nag and repeat yourself a million times. Let him know why you feel the way you do without casting all the blame on him, otherwise he will shut down again.
That being said, you also have to honor your feelings, but it's important to know that timing is everything. Best of luck to you. If you love each other, you'll eventually learn how to communicate better.