Dan Savage broadens the definition of normal sex:
Ambinder assumes two points here without, I suspect, even realizing it, so obviously true are those assumptions to him: first, that it’s important for one’s sex life to be "interesting"; and second, that "interest" derives from variety and novelty of partners.
The category of the "interesting" is an aesthetic category — indeed, if Kierkegaard and Auden are right, it is the aesthetic category — but what if sexual experience is misconceived by being interpreted aesthetically? What if an aesthetic understanding of sex is an impoverished one? And even if one does think about sex in such aesthetic terms, why assume that novelty and variety are the only things that interest us?
Well, they're not the only things that interest us in sex. But for men, for evolutionary reasons, they rank pretty high. This is not news. How we manage that natural drive with social norms is the tricky part. And it will always also be messy.