We frequently have this conversation while she’s looking over her shoulder:
“Why can't you stay hard back there? Most guys love doggy-style.”
“I’m not most guys.”
“Obviously.”
“I guess jerking off to Penthouse conditioned me to get hard for faces and tits, not asses.” 

But tonight? Boner pills!

Kneeling behind her, I ease my stiff cock inside, pumping slowly before grabbing her shoulders and pounding her pussy without mercy.

“I don’t want to cum too soon,” I gasp, pulling out.

Searching for her slick seam again, my dickhead grazes her asshole.

“We’ll get there eventually,” she quips. “Just not tonight.”