I've been with a man for three years, and sometimes I wonder how a man's body scent does not smell like a woman's. I told him if you are with somebody for over ten years, you start to smell like them or look like them. My question is that once you are having sex with them for a while, why is it that you can't wash their scent off you no matter how much you wash your hair and body?

Your question was really difficult to understand, but I edited it down as best as I could. I hope I interpreted it correctly.

Some people do believe that the longer you stay with a partner, the more you start to incorporate their characteristics. This may or may not be true, but there are several factors involved. The most significant factors have to do with the amount of sharing takes place between the partners involved. When you are with somebody for years and years, chances are you share a lot of your stuff. Many long-term couples live together. This means you're using the same soaps, laundry detergents, shampoos, hair products, toothpastes, and other hygiene products. This accounts for a lot of how we smell. In addition to that, it's likely you also share a lot of meals and eat a lot of the same things. You might also adhere to similar sleep and work schedules. Basically, you wind up living very similar lives, and this can affect your body odors.

So it's not that a ten-year-old coating of vaginal juices is going to permanently fragrance his genitals. It's more likely that he'll be washing those vaginal juices off with the same soap as you'd use to wash near your vagina.