Honestly, I hope my roommate's dog dies.
Oh, why do you want it to die?
I want to fuck his girlfriend
You shouldn't hope that his dog dies or want to have sex with his girlfriend. Those are both horrible things and your roommate doesn't deserve either.
The dog will die eventually, I bet the dog will die soon in a very weird way. The dog hates me and I hope it gets hit by a car or something.
It sounds like you might have a serious problem if you wish for an animal to die. I think you should talk to a professional because those types of thoughts are really harmful and dangerous.