Why does it always happen like this?

I'm really curious. Why does it always happen in this way? It was as if i was really there. Yet again, i dreamt of someone whom i don't even know who she is. I couldn't see anyone familiar except for my cousin. I wonder if in real life, the person that i dreamt of is her friend. Well, let's get into my dream alright? We were in a train, MRT it was. I was sitting beside her. I was also sitting with someone whom i know but i couldn't really remember who it was. She initiated the conversation. She said that she's not what i think of her. I also don't know what i think of her. Anyway, she started talking about being together and all those 'being-a-couple' stuff. If i were really in that dream, myself, controlling my own body, i would totally agree with it. Because i think she's a nice person, she's beautiful. But i said the exact opposite thing. I didn't deliberately said 'NO!'. I told her that i have a major examination coming up, A levels, and that i do not want to indulge myself in such relationships. I then apologized. She then stood up and went to another cubicle of the train. I didn't follow her because i thought that i should give her some time to process what i just said. Then, i heard screams. I quickly ran to the cubicle that she went and saw her lying on the floor, blood all over. She had just cut her wrist. What on earth was she doing? My cousin was there, attending to her, calling for help. I tried to find something to stop her bleeding but couldn't. And then, i was back in the real world. One heck of a narrative essay huh. Well, this dream did happen to me. Why are all these dreams coming? Do they signify something? Why don't they happen to me in real life?