As a guy that actually has been through the same thing as your boyfriend. While I was still very much psychically attracted to my ex fiance, sex became a chore. It wasn't fun anymore, I gave up trying to spice it up. She never bothered to dress up or anything for me anymore, nor did I for her. Us guys are very visual and logical creatures. Women try to appeal to our emotional sides and it rarely works. We want what we can have, honestly once I realized that I couldn't have sex with my ex anymore, I was more sexually attracted to her. While the distance would definitely put a strain on things, give him something to look forward to. Tease him a lil, he knows he can have you. Give him a night he can't forget and break your routine. Routine kills relationships.