Women submit to male (not only husbands) demands for sexual favors when they don't really want to all the time! That doesn't make it rape.
A man has a RIGHT to demand sex from his wife in the same way a woman has a RIGHT to demand sex from her husband. The right does not create the obligation. However, if a man, or a woman, understands the ramifications of saying no too many times, either one will have sex with their spouse, technically against their will.
Theres a difference between you giving in to me when I nag you for sex, and when I slam you against the wall and just take it.