What do you think is a fair way to split the rent?

I just found a set of roommates for graduate school and they should be great, I’m super excited. It’s an engaged couple, so we’re looking for a two bedroom apartment. What do you think is the fairest way to split the rent and why?

They also have a small dog. If that matters. I have no pets. (The one I’m always calling mine is my boyfriend’s really.)