He needs to go to the apartment office and ask for a replacement mailbox key. It might cost him a buck or two. It's not about the key. Does he disrespect you in other ways? That's why you would have "over" reacted to this. Isn't he an adult? If he were living on his own, he would have gotten his key replaced without insulting anybody about how attached they were to their key. If he had been a little more attached to his own key, he wouldn't have had this problem to begin with, eh? (Okay, that last smart remark maybe why I live alone!) I'm glad you made up, maybe not a big deal if things are usually cool. I would have to have my own key for when I come home & pick up the mail. I MIGHT be a little suspicious about how he lost it.