Their problem is that she doesn't open up to him and doesn't trust him, bevause he doesn't do that to her either, it's like they created a barrier between themselves, it's both their faults, but the big problem is the way he's reacting
Girl, if thats how you feel, then you really need to work on that. Its like anything, it gets easier with time. If you have a relationship that you believe will shatter, should you are true to yourself and your feelings, then that relationship is doomed to fail. By not being open and honest, you are either denying yourself happiness in your relationship, or holding yourself back from find a person who actually make you happy
Its actually pretty difficult to speak up, like you guys say "communication is key" or "why cant they talk things out??" In my opinion it's really hard to speak up about how you feel with someone you care about because of said misunderstanding or some other reason.. Like think of a time you wanted to speak up but couldnt bring yourself to.