Dream About Boyfriend Secret Girlfriend Yak Attack

It started off as a cute dream about me and my boyfriend, Tristan. He was his normal sweet self and promised marriage at some point. Later in the dream, I find out he's actually had a different girlfriend this whole time, and somehow has been living with us in secret. So, I was very disturbed and unhappy, and kept trying to find a way around it/out of it. The other woman heard me ask him to leave her and she threw a fit saying she was here first. Then a giant Yak came in, it was angry and so I turned and ran to lead it out of the house and then hid under something small while the bull Yak attacked. Next thing I know, I'm trying to talk to Tristan about it again and he keeps going our for a cigarette. Keep in mind that Tristan in real life does not smoke cigarettes and there is no other woman in real life. I mentioned how he said we would get married and asked if that was a lie and he would try to go outside to smoke a cigarette.