I was wondering if anyone (on either side) has experience with this and how they have dealt with it. 

Prior to progressing to a relationship, we talked, a lot, about anything and everything. My SO has told me that they have never opened up to anyone as much as they have with me, but they have closed up since we have progressed. They have told me that they feel like they can't do both, although they really want to. 

To make things tougher than they are, ours is a long distance relationship, making it difficult to communicate at the best of times.