Is sexual privation a form of spousal abuse? Why or why not?

Just so that some of you people don't make ignorant assumptions: My situation is opposite of what you might think. After making this clear before marrying my wife years ago, it was a fundamental before the marriage took place. Now that my age is showing, my wife started getting in my face and making demands in this area. Thankfully Viagra works. She says when the day comes that Viagra doesn't work, remember that the mouth still works when nothing else does. For her sex is a misdemeanor: Da more she misses, da meaner she gets. Dang, it's like freaking Jekyll and Hide.

That the word "no" doesn't exist works both ways.