I'm not too sure if I can fully answer this, for in my relationship everything is pretty open until we fight. Unfortunately now is one of those moments so hopefully my judgement isn't too clouded. Though to be honest I suppose I make more walls than I break.
From what I can figure out in my experience, a way to get by emotional walls is to sincerely care about the other persons thoughts and feelings. Even if their thoughts and feelings seem dumb or senseless to you, and you think it isn't important. It's very important to them, and people don't like their feelings belittled. You have to try and understand from their point of view: Talk to them, listen to them, and try not to be biased about it. If someone expresses their worries to you about something, one of the worst things you can do is to crumple it up and throw it in their face. Take a break to cool off if you need a few minutes but don't flat out abandon them when they need you. If you are reliable, trust worthy, and willing to communicate with someone they will open up to you in time.