What could have happened

So there was this girl I was chatting with on Facebook for a while, and well here is what it was like, we talked occasionally and she'd often disappear half way through the conversation, I didn't understand why she did that and automatically resorted to thinking she just didn't like me or thought I was annoying, but then sometimes she'd attempt herself to start a conversation only to do the same thing yet again. Yesterday she sent to me saying how she's tired and wanted to die, so I told her I was here to listen, and so we went on to spend the entire day talking about various things including her negligent boyfriend, whom I advised her to break up with due to how unabashedly he was ignoring her, so anyway I got a little drunk at night and sort of fell asleep during the conversation (something she herself did with me before plus the aforementioned incidents of her mysterious disappearances) , and then I woke up to find out she has blocked me: her name was replaced with Facebook User in the messenger and I wasn't able to send her back any messages or even find her when I tried to search for her. Nothing else happened, she was the last one to message me and she even told me how she was telling her boyfriend that they should break up. I read this message after I woke up and before realizing that she blocked me. What could have led her to do such thing ?

I would say she didn't like your advice and decided to block you.

It sounds like she is very troubled and you will waste a lot of energy trying to figure out what happened with someone who is probably not stable. You cannot control other people and sometimes they react to something but it has little to do with you.