DEAR MISS MANNERS: My fiancé and I will be hosting two friends in our new home. We have one guest bedroom, and plan to set up the other person on an air mattress in our living room. Both soon-to-be-guests know the situation. One of them has been repeatedly texting us, adamantly requesting, and even trying to guilt us into saving the guest bedroom for her. We were initially planning on giving her the room, but quite frankly, I’m so annoyed now that I’d rather give it to our other friend. What is the proper etiquette when you’re going to be a guest at another’s home? Is it acceptable to demand a…