First, fireplace is in build mode, click on the fireplace on the house in there. Second, it depends on what you want the husband to do. You can go either way with it, experiment. He can leave his wife or have the girl over and start a fight. I don't have much imagination, but I this game sometimes brings it out of ya. lol. It also will not affect anything if you do not have your sim act on it. I have found romantic interests alot of times in my friends list. I just left them there, or met them somewhere and ask to just be friends and that usually takes care of the heart.