Crazy dream?

I had a dream that a girl I go to school with happened to be friends with my boyfriend (not in real life tho). Anyways the two of them propositioned with each other right in front of me! Then did the deed right in front of me!! The girl winds up getting pregnant with his baby! I am so upset in my dream at the both of them. I ask my boyfriend why would he do this to me, he says that he "isn't going to leave me, though I know your upset but this is the most beautiful girl I have EVER been with." And I tell him he has ruined everything and I actually break up with him.