The magic thing about relationship is odor. I read an article, saying a girl always wears a huge tshirt which obviously doesn't fit her. She even always show off her t-shirt to others, let other smell it. In fact, that's her boyfriend's t-shirt with his odor. Same thing with woman's odor. I'm thinking of ways to make the significant other smell you except sending your t-shirt or underwear to her or him. It would also be interesting to keep and store the odor of your ex boy/girl friend, just as you shoot erotic video to keep the memory.
Need to do some research on it... One interesting industrial design I came across, but has nothing to do with odor, http://zinoopark.com/ check the project: erotic dish.