On Being A Good Friend (A semi-rant)

Which I am shitty at.
I'm not a romantic, or if I were, I'm a romantic only because any other option makes life less than it could be. I prefer truth, hard cold truth that you can use as a crutch to pull you out of despair and into real life as a genuinely good human, the way of becoming a classical hero.
I'm a romantic about friends though.
Maybe it's because I haven't really been through it enough times, the day in day out of being real friends with somebody to the point where you know each other well enough to expect each other's moves but still be amazed at the contradictions in their behavior and the paradoxes in their thoughts but you still love them anyways.
I've had one friend for that. I don't mind that.
I've been listening to Charlie's Last Letter alot this week, particularly because I keep feeling alone when I'm surrounded with people that now like me but don't know me but I want to know them. There's this line that always sticks with me about how "driving with the people you love most in this world" that makes me wish I could know more people like that and love them for it.
But they don't let me or maybe I don't know how to let them and I'm shitty at helping them through bad times so of course they won't trust someone like me.
For the last several months, I've lent one of my favorite books to a friend of mine from Creative Writing. I lent it the day before Winter Break, she still hasn't given it back to me. I message her asking for it, she messages me back and we decide that she can drop it off at my house. In that message, she says "There's been alot going on" and then I feel like shit because I was supposed to be there for her and at what point I was there for her because she told me a terrible terrible secret that I kept with me. I thought that meant we were friends and we are and in the hall, she sees me and promises me to give it back today with an explaination, I hope deep down that maybe it'll work out. But it doesn't. She didn't drop it off today at all.
The weird thing is that I don't really blame her, I'm mad at myself for somehow losing her trust and screwing up what could've been a good friendship.
In DVP, there was this girl that I was kinda friends with (See, I don't know what friend really means anymore. An acquataince you talk to in class sometimes? Someone you give your deepest darkest secrets to? I don't know) who was texting her mom about something serious, and looked really really tired and sad. I scribbled "Are you okay?" in Sharpie cuz I felt bad and I wanted to help, but she said no and "Thanks for asking though." Somehow, Mr. Russo tells her something (I'm assuming it was permission to go to the bathroom and asking about the problem. He's a really chill, cool guy) and then she leaves the classroom with her face red and eyes blinking. Her best friend S immediately asks her group to continue editing, and then leaves the classroom. They don't come back before the end of the period.
Meanwhile, I'm sitting there feeling like shit for not being able to do anything but embarrass myself and crack a few jokes.
The weird thing is that none of my "friends" (except for that one I keep mentioning) have ever done anything remotely similar to that except for the friend I lent the book to in Creative Writing. At least then she let me help and I tried to be there, but soon enough that was gone too.
I don't want to see my friends breakdown or anything, it's just that everyone's human and I don't think I see that side of people. It's like I'm friends with people when their in a good mood and they suddenly disappear when they feel like shit or they hide it from me too well for me to notice or help.
I don't know what to do.