Why did my loved one kill people in my dream?

Last night I got a lot of sleep and I kind of woke up at 10am and decided to sleep in 'till noon. Well! When I went back to sleep, I suddenly was in college (I am a Senior in High School). I went outside I found my boyfriend fighting with his ex-roommate from last year and then he got out a gun. Knowing he wasn't aiming to kill me I ran into this small room... where his ex-roommate followed me... so I ran to the other side of the room and my boyfriend starts open firing at his ex-roommate. His ex-roommate was shot several times, but not killed. So my boyfriend stepped out of the room and pulled the pin on a grenade. I was still in the room with his ex-roommate and I reached for my boyfriend and he pulled me out. After he pulled me out we went back in the dorm and I noticed our clothes were completely clean, and he pulled out a knife and told me not to tell anyone. That did frighten me a bit, but I nodded my head and went on. Later in the dream I tried to tell several people, and they didn't seem to care, but then I went to the movies by myself and met my boyfriend there (for some reason I had a cigar and a V.I.P. wristband)... I hid the cigar from my boyfriend and the dream kind of ended somewhere around there.