Now, if you haven't figured it out quite yet, I am drawing a fair amount of parallels to the infamous Hogwarts castle from Harry Potter. Whether or not this makes sense to do this, I don't quite know many other castles to make this analogy with. So I am taking this paragraph to apologize for any disconnects that I have caused by this. But for those of you who know about places such as the Room of Requirement and the Astronomy Tower, I think this may have some value.
Some people are perfectly willing to open up the gates to their castle and let in anyone who wants to join. However, there is the opposite end of the spectrum to consider, the ones who let no one in whatsoever. These are the people that are troubling to me, maybe not so much because they don't let people in, but rather because they allow people to see certain things about themselves without ever letting them in. They let you look through the gates and gaze down from the mountains and you can get a good glimpse of what their "castle" is all about, but you don't actually know anything about it.
In a healthy relationship you would allow your closer friends into some of the more private rooms, such as Gryffindor Tower or the Room of Requirement. And likewise, The person you marry, you would end up sharing your castle with, even allowing them access to the Headmaster's office. Basically, the more intense relationships allow for more access inside of this "castle".
The goal is to have varying degrees of relationships on your life in order to have people to lean on when you need them. Because at some point or another, in this crazy world we live in, our castle is going to be under attack. It isn't pretty, it isn't fun, but it is the truth. Granted, it may be feeble attacks, they are attacks nonetheless. And why it matters that we let people into our castle is this. When we do undergo a large attack on our "castle", and make no mistake, we will, we have people backing us up. We have people on our side, people to protect us. Otherwise, we are left to fight the world by ourselves. Otherwise, our castles will burn, and it becomes ever harder to let people in. It becomes almost impossible to face our castles ourselves. Then you are left wishing you just had a new castle, but that's the funny thing about it. We only get one chance at a heart, so we have to value it more than anything.