Though the poster of this thread could have worded this differently, I'll answer anyway.
I would never give "pity sex" to some one in a wheel chair, but I was in a relationship with a quad for some time. He was lucky enough to be able to feel everything and get and maintain an erection, he just couldn't move much more than his arms. I was very attracted to him physically as well as mentally and we had a lot of fun. The only downside was I had to do most of the "work", but the bonus was he was really good with his mouth. This included dirty talk, being dominating verbally, telling me exactly what to do, as well as being able to use his mouth expertly in physical ways. Not only was he an amazing kisser, but he gave me the BEST oral sex I have had to date. Needless to say, sex was never a problem. It was fun figuring out new and interesting ways to pleasure each other.