For the record, gay people can totally get married and have children. Well, they will be able to, once our various governments get their heads out of their respective posteriors, anyway, and let them get married and adopt kids.
Not wanting romance is not exclusive to the autism spectrum. Some neurotypicals don't like romance, either.
It's kind of like the flip side of asexuality--Instead of being romantic asexual (don't like sex, but do like romance--about 4/5ths of asexuals are this way), you're aromantic sexual (don't like romance, but do like sex).
This does make you just about as incompatible with most people as an asexual person is... you'd need to find other people who want just sex, and no romance, in order to avoid leading someone on.
Being asexual, I don't really see the point of sex without a personal connection... it makes me think of a cat in heat, just having sex because that's what the hormones say. So, I guess I can't really understand why you want to have sex but don't want a relationship, but I know it's within the scope of human sexual behavior--I may not get it, but it does exist. Just please be responsible--just because you don't want a relationship, doesn't mean you don't still have to worry about using protection and being respectful of whoever you happen to hook up with, or become friends-with-benefits with, or whatever.