My FI's coworker/friend is going through a divorce but still lives with his wife. To my understanding, they are not trying to reconcile, but live together until their house sells or their child graduates or something. We're not sending out our invites for about two months, but the chances of them still living together are high. So, would I address it to Mr. and Mrs. Joe Smith OR Mr. Joe Smith and guest. He told my FI the latter, but I think it is rude to send an invite to their house with just his name on it. I thought maybe I could send it their work instead. What is the etiquette on this? TIA.