Friendship?

Recently I've been emotionally suffering because of a friend. Relationships are complicated for sure but it is confusing when a person you regarded as a friend turns out to be "just someone you know".

She's actually my current roommate. I thought we were friends that could talk face to face...
     Right before December she told me on the phone she has been offered a new rental apartment and she will move out in January. Due to this I have no other options than to move out too because of multiple reasons, first of all I don't have the money to pay the rent of our current apartment. And, since it was such a short notice finding a new apartment was extremely stressful. The rents are too expensive, there are not many available apartments for the students... The list could go on and on. Luckily, couple days ago I was offered a rental apartment.
     The worst thing is she said we should sit down and talk things through about some issues related to the moving out... That never happened. All she did was to send few text messages.

This has made me think about friendship. and what it does mean to me. These moving out news made me realize that the person I regarded as my close friend is actually as a distant person as an acquaintance from the university. Who waits till you leave the house to send you a text message to inform you about something? Now that I think about she started avoiding me about a year ago: Sending me text messages only when necessary, trying not to come out of her room when I wasn't in my own room.
     Friends aren't like that, right? At least I don't think friends should be this distant. Naturally one is not equally close with all of their friends but there is a great difference between being friends and acquaintances. I think that when interacting with people there is this sort of a barrier that makes one to keep their distance to acquaintances. With friends this barrier doesn't even exist.
     I'm not sure how to explain how I see the essence of friendship. I have many friends I see/contact extremely rarely (every couple years...maybe?). But still, they are my friends, though naturally with different friends we share different interests. It is easy to talk to them; even after long time I feel I don't need to think what I should say.
     In conclusion, friends are friends and they will always be there for you and you don't need to keep up the invisible barrier.

My apologies for the blabbering. I felt I needed to get these thoughts on paper and I'd be glad to hear your thoughts about friendship and I you've ever had a one sided friendship do feel free to share your story.