Ouch... you're right, the popcorn smell is hard!
Sure you can ask your husband to change. BUT... whether he agrees or not is in his hands, not yours. Maybe he will choose another snack, and maybe he won't.
So, to take better care of yourself - try to think ahead about some things YOU can do in this situation. You can only take control of what YOU do.
Maybe, like you did, physically remove yourself to another room (maybe it makes him realize he really makes things hard for you and you are serious about it). Maybe log in to SparkPeople on real time, or find someone to chat with. Maybe journal, concentrating on the positive and reminding yourself, why exactly you choose not to join him in snacking, and all the things you do for yourself that are better than eating popcorn. Or find another fragrance, something not food-related, and enjoy it...